ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 377 



gut, a small one in the seventh segment,, a larger one in the eighth and 

 ninth segments. The respiration of the former may be carried on 

 through the trachea supplied by branches of the right and left visceral 

 trachete. The larger area is supplied through the branches of the right 

 and left dorsal rectal trachea and the right and left lateral rectal tracheae. 

 There are also caudal gills, and respiration may take place also all over 

 the surface of the body through the thin wall. J. A. T. 



Rectal TracheaB of Dragon-fly Larva.^jANET P. Jamieson {Froc 

 Acad. Nat. Sci..\Philadelphia, 1918, 81-.S-1, 2 figs.). The rectal epithelium 

 of the larval Argia talamanca, which lives by waterfalls, has three main 

 longitudinal folds. There are two main longitudinal trachea, the 

 branches of which are traced. All have a black pigment. J. A. T. 



Hind-gut and Rectal Tracheas in Dragon-fly Larva. — Mitchel 

 Carroll {Proc. Acad. Nat. 8ci. Fhiladelphia, 1918, S6-10?>, 6 figs.). 

 An intimate description is given of the hind-gut of Mecistogaster 

 modestus. Six divisions are recognized, five of them with epithelial 

 folds. The distribution of the trachea is dealt with. The tracheole 

 supply of the hind-gut is not rich. All the tracheal twigs end on the 

 basement membrane side of the thick columnar epithelium. The 

 only part of the rectum that has a tracheal supply is the columnar 

 epithelium. It seems improbable that any diffusion takes place between 

 the gases in the rectal tracheoles and those in the water in the rectum. 

 Yet the larva can live without their caudal gills. Perhaps the blood in 

 the longitudinal folds of spongy or reticulate tissue captures oxygen 

 from the water in the rectum. J. A. T. 



Experiments on Respiration in Larval Dragon-flies. — Joseph H. 



BoDiNE {Proc. Acad. Nat. Sci. Philadelphia, 1918, 10o-12, 3 figs.). 

 Zygopterous larva (Ischnura and EnaUagma) breathe by means of the 

 rectum from the time of hatching until transformation. Caudal " gills " 

 serve only in a mechanical way, as rudders in the locomotion of the 

 larva. Respiration through the skin of the larva is doubtful, but if it 

 takes place it is only in a slight degree, not supplying enough oxygen 

 for the respiratory needs of the larva. Ptegular rhythmic contractions 

 of the rectum take place throughout the aquatic life of the larva. The 

 rhythm of rectal contractions is not interfered with by removal of the 

 caudal "gills." J. A. T. 



Spermatogenesis of an Orthopteron. — ^J. Machida {Journ. Coll. 

 Agric. Univ. Tokyo, 1917, 6, 215-44, 3 pis.). The phases of 

 spermatogenesis in Atractomorpha bedeli are described in detail. The 

 first spermatocyte mitosis is a transverse reduction-division ; the second 

 is a longitudinal equation-division. The longitudinal cleft in the 

 spermatogonia at least appears to be a true longitudinal split. Some 

 deeply stained nucleoli always appear in every resting stage of the 

 spermatogenesis after the chromosomes have diffused, but these bodies 

 do not seem to give rise to the accessory chromosome or any other. 

 The accessory chromosome is distinctly seen in the telophase of the 

 secondary spermatogonia. Throughout the growth period and the 



