ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 635 



determining the number of polar globules in ova wbicb, witbout being 

 fertilized, become developed into male animals. For tliis purpose, as 

 for some otiiers, tbe egg of tbe Honey Bee is well adajited, and it is 

 bere always easy to keep tbe unfertilized from tbe fertilized eggs. Tbe 

 first polar nucleus always remains undivided, as is tbe case in some 

 otbcr Insects ; in Ajjis tbe second polar nucleus often appears to be 

 divided. Tbe fact tbat tbe tbree nuclei are not, as in some cases, due 

 to a division of tbe first nucleus is proved by tbe position of tbis nucleus, 

 wbicb is always found just under tbe surface of tbe egg and separated 

 by some distance from tbe otber two. Tbe female pronucleus soon 

 becomes vesicular in form, and makes its way to tbe axis of tbe egg, 

 wben it becomes converted into a spindle, and by fnrtber divisions gives 

 rise to tbe nuclei of tbe blastoderm-cells. Tbe polar nuclei undergo 

 changes similar to tbose seen in Musca vomitoria ; tbey do not, bowever, 

 become vesicular in form, but approach one another and are inclosed by 

 a rather large vacuole of tbe superficial protoplasm wbicb is free from 

 yolk. In tbis vacuole tbey break up into fine chromatin granules wbicb 

 are tben scattered tbroiigb the whole cavity of tbe vacuole. We may 

 suppose that tbe contents are, later on, removed from the egg. 



In fertilized ova tbe ovarian nucleus undergoes tbe same division as 

 in tbe unfertilized. The result of tbe investigation — that the unfertilized 

 ova form two polar globules — or, more correctly, two polar nuclei by 

 two divisions of tbe ovarian nucleus, is confirmed by tbe results wbicb 

 Platuer has obtained with Liparis dispar. 



With regard to tbe bearing of these observations on tbe tbeories of 

 Weismann, the author says that be thinks it is better to extend tho 

 investigation in all directions, and only afterwards to construct a theory, 

 instead of basing an extensive speculation on a limited number of facts ; 

 tbe sptculatiou, indeed, is only too soon shown to be untenable, as it is 

 in contradiction to observed facts. 



Respiration of the Ova of Bombyx.* — Profs. L. Luciani and A. 

 Piutti have made an elaborate series of experiments on tbe respiratory 

 phenomena in tbe ova of tbe silkworm. Eespiration is slight during 

 bibernation ; at tbe ordinary temperature of 8°-10^ C, a kilogramme of 

 ova i^roduced only about 18 centigrammes of CO2 in 24 hours. Tbe 

 respiratory activity is lessened by lowering tbe temperature, by desicca- 

 tion, and by restricting the space. Both cold and drought induce 

 " absolute- latent life," wben tbe respiration ceases. During artificial 

 incubation, witb a gradual rise of temperature, tbere is a regular increase 

 in tbe quantity of CO2 given ofl' per unit time, till towards hatching tbe 

 amount is 259 times greater than that at 0°C. during bibernation. Tbe 

 respiratory activity also varies witb tbe developmental activity. Tbe 

 relation of tbe CO2 exhaled to the oxygen absorbed — tbe " respiratory 

 quotient " — is expressed in a fraction increasing to unity and beyond that 

 as development progresses. Tbere is therefore in all probability a pro- 

 duction of less oxygenated molecules and an increasing sum of potential 

 energy. 



Termites.f — Prof. B. Grassi bas a preliminary note containing 

 furtber information on tbese interesting insects. He finds tbat colonies 

 of Termites annually produce an enormous number of sexually mature 



* Bull. Soc. Entomol. Ital., xx. (1888) pp. 69-99. 

 t Zool. Anzcig,, xii. (1889) pp. 35.5-61. 



2 Y '^ 



