ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 41 



she with little hesitation selected for a mate the one with the largest 

 balloon, taking a position upon his back. "After copulation had begun,, 

 the pair would settle down towards the ground, select a quiet spot, and 

 the female would alight by placing her front legs across a horizontal 

 grass blade, her head resting against the blade so as to brace the body 

 in position. Here she would continue to hold the male beneath her 

 for a little time, until the process was finished. The male, meanwhile, 

 would be rolling the balloon about in a variety of positions, juggling 

 with it, one might almost say. After the male and female parted com- 

 pany, the male immediately dropped the balloon upon the ground, and 

 it was greedily seized by ants." 



The only known case at all comparable seems to be that of the 

 allied Hilaris sartor Becker, where, as Mik and others have described, 

 the male produces a real web which is borne by the hind feet and 

 serves to assist the fly in the son. 1 e what peculiar gyrations of its flight. 



Metamorphosis of Insects.* — Dr. J. E. V. Boas briefly discusses 

 this difficult subject. He points out that while in hemimetabolic insects 

 the larva shows a general resemblance to the adult, in holometabolic 

 insects the larva bears to the imago a relation comparable only to that 

 borne by degenerate parasitic insects to typical forms. In the former 

 case the larva resembles the adult more than it resembles any other 

 insect ; while in the latter, larva and imago have specialised along 

 different lines, and cannot be directly compared. The cause of the 

 great distinction between larva and imago the author seeks chiefly in 

 the wingless state of the larva, but also in the fact that the larva is 

 chiefly nutritive, and the adult reproductive. The pupa is to be 

 regarded as an incomplete imago, analogous to the sub-imago stage 

 seen in the development of the Ephemeridae. The limitation of the 

 power of growth to the larval stages produces a marked contrast to 

 the metamorphosis of Crustacea, where the final form is attained while 

 the animal is still exceedingly small. This fact the author again 

 correlates with the winged condition of insects ; for the wings are dead 

 chitinous plates which could not be reproduced after a moult. As can 

 be seen by the above, Boas entirely agrees with Fritz Miiller in regard- 

 ing the incomplete metamorphosis as the more primitive state, from 

 which the holometabolic condition has been evolved. 



Striped Muscle of Insects.f — Dr. Giinther Enderlein has studied 

 these in various larvae belonging to the CBstiidse. He finds that the 

 majority of the muscles show the following remarkable modification. 

 The muscle-fibres consist of one or several bundles of fibrils imbedded 

 in the middle of a sheath of sarcoplasm, which is quite distinct from the 

 sarcolemma. This sheath of sarcoplasm is divided into compartments 

 by transverse lines, which are continuous with Krause's membrane. 

 These transverse bands are further intimately connected with the sai co- 

 lemma, so that Krause's membrane is formed by an ingrowth of sarco- 

 lemma. 



Temperature of Insects. J— Prof. P. Bachmetjew has made a long 

 series of observations on the relation of the body-temperature in insects 



* Zool. Jabrb. (Abt. Syst.), xii. (1899) pp. 385-402 (1 pi. and 3 figs.). 

 r t Arch. Mikr. Anat., lv. (1899) pp. 144-250 (1 pi.). , 



% Zeitschr. f. wiss. Zool., lxvi. (1899) pp. 521-604 (5 figs.). 



