ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 749 



into two. In the early segmentation mitoses, the haploid number (10) 

 of chromosomes is found. 



Since it is known that some parthenogenetic individuals lay eggs 

 which all develop into females, and others lay only male-producing eggs, 

 and since the female shows the diploid chromosome number in all its 

 cells, while the male has the haploid number in the spermatogonia and 

 nerve-cells, it is suggested that the eggs which undergo no maturation- 

 division become female, those which undergo reduction males. 



Tabanids and Trypanosomes.* — Sir David Bruce and Captains 

 A. E. Hamerton and H. R. Bateman find that Tabanus secedens, 

 T. thoracinus, and T.fuscomartj hiatus do not seem to be able to trans- 

 mit Trypanosoma pecorum from infected to healthy cattle by the 

 mechanical method of transmission. Owing to the short life of these 

 Tabanids in captivity it is impossible from the experiments made to 

 state whether they can convey the disease after a period of development 

 of the Trypanosomes in the fly. The investigators believe that the three 

 types of Flagellates found in Tabanus secedens and T. thoracinus are 

 various stages in the development of a harmless Crithidium in these flies. 



Revision of Oriental Species of Tabanus.f — Gertrude Ricardo 

 has done a useful piece of work in revising the species of Tabanus from 

 the Oriental Region. The 119 described species are reduced to 7:5, but 

 the addition of 40 new species raises the total again to 117. 



Influence of Weather Conditions on Frequency of Warbles. $ 

 X. Lehmann and C. Vaney have made careful computations of the fre- 

 quency of warbles in different seasons. Their general result is that in 

 the region of Lyous, warm weather during July and August favours the 

 oviposition of Hypoderma bovis, and is followed by a high percentage of 

 warbled hides the following year. 



Respiration and Circulation in Tipula maximaj — J. M. Brown 

 describes the respiratory and circulatory systems in this larva, a form of 

 " leather jacket," which occurs beneath stones, eitber close to or in the 

 bed of streams. There is an extensive system of fine air-tubes taking 

 origin from the stigmatic chambers and radiating to the body-wall. 

 Amongst these tubules the blood circulates. This may be an adapta- 

 tion for bringing the blood into relation with the air near the spiracles 

 themselves. There are " blood-gills " for respiration when submerged. 



The author gives a careful description of the "heart," or dorsal 

 vessel, the intersegmental and ostial valves, the pericardial cells, which 

 seem to be in great part excretory, the pulsations, which occupy about 

 2*5 seconds each (about 24 per minute, the resting phase occupying 

 about half the whole period), and the action of the ostial valves. 



* Proc. Roy. Soc, Series B, lxxxiii. (1911) pp. 349-58 (1 pi.). 

 t Records Indian Museum, iv. (1911) pp. 111-258 (2 pis.). 

 % Comptes Rendus, clii. (1911) pp. 1508-10. 

 § Trans. Linn. Soc. (Zool.) xi. (1910) pp. 125-35 (3 pis.). 



Dec . 20th, 1911 3 c 



