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The Pamphlet Collection of Sir Robert Stout: Volume 73

Art. XII.—Note on the Vegetable Caterpillar (Cordiceps robertsii). — Plato VIII

page 155

Art. XII.—Note on the Vegetable Caterpillar (Cordiceps robertsii).

Plato VIII.

In the discussion which followed the reading of Mr. Maskell's paper on the 14th November, I maintained, in opposition to that gentleman's definition—"animal at one end, vegetable at the other"—that the so-called Vegetable Caterpillar, as we now find it, is entirely vegetable substance. The author, as I understood him, contended that the body of the caterpillar had become permeated with vegetable tissue, but that the outer integument or skin was still dried animal matter. To put an end to any possible doubt on the subject, I forwarded to Sir James Hector a specimen of the Vegetable Caterpillar, and asked him to get it examined and tested by the Government Analyst, for the purpose of ascertaining its true constituents. The following result has been officially communicated to me:—

Mr. Skey.

The question at issue is, whether the skin of the caterpillar remains, or if it has been converted into fungus like the soft internal tissues. The presence or absence of chitine will determine the question. Save the specimen for reference.

James Hector. 22/11/94.

Vegetable Caterpillar.—For animal matter in the so-called skin.

The skin does not give any indication of the presence of chitine or other animal substance. It burns without intumescence, and does not evolve the odour of nitrogenous matter in combustion.

William Skey. 23/11/94.

In the course of my remarks at the meeting I stated that I had dug up in the woods hundreds of this singular product, and that in every instance that had come under my observation the caterpillar, in the living state, had descended into the ground tail-foremost, the stem of the fungus afterwards springing from a point between the back of the head and the first fold of the neck, and then ascending vertically to reach the light. Since that date I have been examining the specimens in my collection, and I have found one very curious I example in which there is evidence of a different proceeding on the part of the caterpillar, with exactly similar growth of the fungus. In this instance the caterpillar had evidently buried itself head-foremost, and then turned its head slightly to the left, whereupon the fungus had commenced its stem-growth at the usual point and travelled upwards in a line page 156 with the body, curving and twisting somewhat before emerging at the surface of the ground.

In most specimens the stem is more or less twisted and sometimes bifurcate before it reaches the surface, after which it assumes a perfectly erect character, the fructification being at the top, 3in. or 4in. of the terminal part being covered with closely-set spores, having externally a granulate appearance. The longest stems I have met with ordinarily measure 7in. or 8in. from the insertion to the extreme tip.

I trust I have made myself sufficiently clear, but the peculiarity I have been describing is better seen on the accompanying plate (reduced from a photograph), in which fig. 1 represents this abnormal form. Figs. 2 and 3 on the same plate exhibit the Vegetable Caterpillar as it is ordinarily met with (upper and lower aspect), the smaller of the two showing the branched process I have mentioned, about an inch from its head. Fig. 4 illustrates the curved manner in which the caterpillar sometimes disposes its body before undergoing its final transmutation into fungus. The body of the specimen represented by fig. 1 measures 75mm., and its stem, measured in a straight line, 150mm. Although the caterpillars are of about equal size, the stem of No. 1, owing to its eccentric manner of growth, is 2.5in. longer than that of No. 2. (The body of the largest of the caterpillars here figured measures exactly 3in. in length.)

The popular notion that the Vegetable Caterpillar is found only under rata and kauri trees is quite an erroneous one. It is abundant in the southern parts of the North Island, where the kauri does not exist, and I have found it in localities from which the rata is entirely absent—for example, in small clumps of bush in the Taupo country. Indeed, it may be looked for in all suitable places, although, as a rule, it is more numerous near the summits of the wooded ranges, the fungus shooting up its little stem, like a miniature bulrush, among the dead leaves and decaying vegetation which cover the ground in such situations, often to the depth of several inches. After scraping away this surface covering it is necessary to dig out the Vegetable Caterpillar very carefully with a sheath-knife, the slightest attempt at forcing it up breaking the stem and destroying the specimen. Sometimes several are found grouped together within a foot of each other; but it requires a practised eye to distinguish the tiny stem among its surroundings of a similar hue. It is often rooted up and eaten by the wild pigs, and in the Taupo country I found the Woodhen digging up and devouring it. When fresh it has a pleasant nut-like flavour.