ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 251 



hypnosis." The insect may be " awakened " by mechanical and chemical 

 stimuli, not by optic or acoustic stimuli. After awakening it is just as 

 lively as usual, which shows that the " hypnotic" state is not a fatigue 

 phenomenon. J. A. T. 



Mitochondrial Changes in Spermatog-enesis. — D. Yginov {G. R. 

 Soc. Biol., 1916, 79, 451—4, 1 fig.). During spermatogenesis in Gryllo- 

 talpa the mitochondrial substance goes through a series of changes like 

 karyokinesis. In a prophase in the young primary spermatocytes the 

 mitochondria fuse into a filament which fragments transversely into 

 segments which condense into " chondriosomes." This is like the for- 

 mation of chromosomes from the chromatin spireme. In a metaphase 

 there is a spindle of chondriosomes which divide under the attractive 

 influence of the centrioles. This " chondriodieresis," like karyokinesis, 

 effects a precise distribution of the cytoplasmic hereditary substance 

 located in the mitochondria. J. A. T. 



Peculiar Occurrence in Spermatogenesis of Gryllotalpa. — D. 

 VoiNOV (6'. R. Soc. Biol, 1916, 79, 542-1, 2 figs.). In spermatocytes 

 of the first order a glolnilar mass was observed in the middle of the 

 chondriosome. It divided into four pieces, which approached the centro- 

 somes and passed to the second spermatocytes, two to each, and then one 

 into each spermatid. Yet in the transformation of spermatid into 

 spermatozoon the mysterious little body was rejected. J. A. T. 



Striped Muscle of Mantis. — II. E. Jordan (Anaf. Record, 1919, 

 16, 217-45, 3 pis.). The wing-muscle of this insect furnishes an 

 exceptionally favourable material for the investigation of the inter- 

 fibrillar sarcoplasmic granules, or sarcosomes, characteristic of insect 

 wing-muscle. They are here unusnally large and abundant. They 

 change their shape and position during contraction of the muscle-fibre. 

 The salient differential features between the leg- and wing-muscles 

 pertain to a conspicuous N-disc in the leg-fibre and sarcosomes in the 

 wing-fibre. The sarcostyles of the muscle are of lamellar form peri- 

 pherally and cylindrical form centrally. Both types contain constituent 

 myofibrils. The sarcosomes are distributed in the intersarcostylic sarco- 

 plasm. The myofibrils are directly continuous with the tendon-fibrils. 

 The N-disc is formed by lateral juxtaposition of intrafibrillar constituents. 

 The sarcosomes are spherical to start with ; they are modified by pressure ; 

 they are in the main analogous to fat-globules ; they become hollow 

 vesicles, which often collapse, suggesting a nutritive function. 



J. A. T. 



Collembola of the Snow Level. — Ed. ITandschin (Revue Suisse 

 ZooL, 1919, 27, 65-98, 1 pi.). Thirty-four species are described from 

 the snow level of the Central Alps, including Onychiurus zschokkn sp. n. 

 and Tetracanthella afurcata sp. n. The Collembola live under stones, 

 among hchens, and among such vegetation as there is ; the chief deside- 

 ratum is-to avoid drought. They feed on decaying plant remains, includ- 

 ing pollen-grains from the Conifers. Springing into the air is only 

 resorted to when the danger is great. There are sometimes great mass 

 movements — e.g. of Isotoma saltans. These may have something to do 



