HAHDWICKE'S SCIENCE-GOSSIP. 



[Oct. 1, 1867. 



living specimens were exhibited to the Eellows ; 

 whilst from information received then and since, it 

 seems that their appearance was general and simul- 

 taneous at a large number of places in the counties 

 of Sussex, Kent, Surrey, and Middlesex. Naturally 

 the first question that arose was, where did the 

 creatures come from ? And in reply to this there 

 were not wanting persons who, connecting their 

 appearance with the storm and the rain, boldly 

 claimed for them a celestial origin, and well-authen- 

 ticated instances of the descent of small fish and 

 frogs from the clouds were adduced in support of 

 the notion ; whilst other persons gravely inquired 

 whether they might not have been produced by 

 electricity— an idea which, though at first sight 

 absurd, certainly does not, upon reflection, seem to 

 be surrounded by any greater difficulties than those 

 of the more fashionable but less novel theories of 

 spontaneous generation. Whilst endeavouring to 

 investigate the subject, I thought it worth while to 

 make inquiries whether anything special or peculiar 

 in the condition of the atmosphere had been noted 

 by meteorological observers; but with the exception 

 of the unusual depth of the rainfall — registered at 

 Kew as 727 inches, but at Steyning as no less than 

 2"44 inches, — I cannot ascertain that anything re- 

 markable was anywhere recorded. But it is worthy of 

 mention that sudden appearances of immense num- 

 bers of these worms took place in the years 1781, 

 1832, and 1845 — on each occasion in the month of 

 June, and immediately after thunderstorms with 

 heavy rainfall ; the prevailing opinions then being 

 that they came from the clouds. Their appearance 

 on June 15th, 1S45, has been described at great 

 length by the Hev. L. Jenkyns, in his " Observa- 

 tions on Natural History." * They were then 

 found upon flagstones as well as on the earth, and 

 were equally abundant upon shrubs and trees as 

 high as examined— certainly 7 or 8 feet from the 

 soil. It is not, however, my present purpose to 

 occupy any more time either in following up these 

 inquiries, or in entering into any speculations to 

 account for the apparently anomalous circumstance 

 of Entozoa being found in large quantities upon 

 apple-trees and gooseberry-bushes ; but it will, 

 perhaps, be worth while, before going into any de- 

 tailed description of what the microscope reveals of 

 their structure, to state in as few words as possible 

 what Natural History teaches us concerning them. 

 They were first recognized as a distinct genus by 

 Dujardin, who, in a memoir published in 1842, f 

 minutely described them, and gave an account of 

 what he considered to be their origin and habits. 

 He was of opinion that they were chiefly parasites 

 of the larva? of the cockchafer, which, he says, are 

 many years coming to their full growth, and that 

 they leave the bodies of their hosts only when 



* Pp. 303, et seq. t Annates des Sciences Naturelles, 1842. 



arrived at maturity, and merely to lay their eggs, 

 after which they speedily die. He accounts for 

 their appearance after heavy rain by supposing that 

 at such times the moisture stimulates the already 

 sick larvse to expel their parasites by contraction. 

 But although this theory might in part explain 

 their being found upon the ground, it does not so 

 well account for their abundant presence on the 

 tree-tops. These worms belong to the family Gor- 

 diacea, in the order Sterelmintha, of the class 

 Entozoa. Formerly they were placed amongst the 

 Nematoidea, in the order Ccelelmintha ; but from 

 the fact that they do not possess the distinctive 

 characteristics of the last-named order, and do 

 agree with those of the first-named, it is rather 

 surprising that they should have been so long 

 allowed to occupy a false position. In the family 

 Gordiacea, the two British genera, Gordius aquaticus 

 and Mermis nigrescens, bear so close a resemblance 

 to each other that it is hardly to be wondered at 

 that mistakes should often be made in identification; 

 and it may be noted in passing that, with the excep- 

 tion of the descriptions already quoted from, the 

 amount of written information concerning them is 

 very meagre, owing, no doubt, to their very retired 

 habits, and to the fact that they have not been dis- 

 covered to be injurious, either directly or indirectly, 

 to man or to his property. According to the various 

 descriptions, the chief differences between the two 

 may be stated as follows: — Gordius attains the 

 length of 7 to 10 inches, Mermis from 4 to 6 inches. 

 Gordius inhabits water or mud ; Mermis is found in 

 damp earth. In Gordius the oviduct is situated 

 nearer to the posterior than to the anterior end of 

 the body ; in Mermis it is nearer to the anterior 

 thau to the posterior. In Gordius the head is 

 much more abruptly rounded than is the case with 

 Mermis ; and, by error, in Science-Gossip, vol. i., 

 p. 197, the tail of the female Gordius is stated to be 

 bifid, whereas male is intended, as I am since in- 

 formed, whilst that of the female Mermis is certainly 

 simple, terminating in a rounded angle, as shown in 

 the diagram. What sort of caudal appendage may 

 be possessed by the male Mermis I am unable 

 to state, since the whole of the fifty or sixty speci- 

 mens in my possession belong to the female sex. 

 Gordius is also of a much darker colour than 

 Mermis ; but both are developed in the intestines 

 of insects, who find the ova and swallow them — 

 doubtless afterwards wishing they had not. On the 

 evening of June 3rd I received by post a small box 

 full of these worms from a friend at Bognor, the 

 letter which accompanied them stating that they 

 had been found in great numbers that morning in 

 the garden after the thunderstorm, chiefly depending 

 in the manner already alluded to, from the leaves of 

 the apple-trees. Specimens were also found upon 

 asparagus, and on bushes and shrubs. On turning 

 them out of the box, I found them to be quite dry 



