ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 31 



Thermic Experiments on Periplaneta orientalis.* — Prof. V. Graber 

 describes a long series of experiments conducted with a view to deter- 

 mining the sensibility of the cockroach to heat. A tin chamber whose 

 ends were kept at different temperatures by water-baths was the appa- 

 ratus, and the results obtained are briefly as follows : — The animals 

 lost power of locomotion at 11-12° C, and death resulted at 5-6° C. 

 (vital minimum). Life, again, was barely sustained with the air at 37° 

 and the floor of the chamber at 39°, a temperature of 41-42° producing 

 death. Other experiments proved the creatures to have a decided liking 

 for situations where the floor temperature nearly resembled the air 

 temperature, and a bad conductor of heat was much preferred as a 

 resting-place to a good one. The optimum temperature seemed to be 

 between 25° and 29° C, though some experiments contradicted this ; and 

 a series of observations in which the animals were allowed a choice 

 between extreme temperatures seemed to show only that they preferred 

 heat to cold, unless the heat was too excessive. 



Diminution in Weight of Chrysalis.! — Herr F. Urech has studied 

 the quantitative relations of metabolism in the chrysalis of Pontia 

 brassicse. He finds that the weight of the chrysalis continually decreases. 

 At a constant temperature, the weight steadily decreases, but the 

 decrease becomes finally more rapid, especially some days before libera- 

 tion. If the temperature be slightly raised the period of chrysalis 

 diminishes. Dry air also shortens it. 



Eyes of Diptera.f — Professor G. V. Ciaccio has published a series 

 of twelve double plates illustrating the histology of the eyes of Diptera. 

 This monographic work includes one hundred and seventy-three figures, 

 each family is figured by itself, with a representation first of the entire 

 organ, and then of the component parts. It is to be regretted that the 

 health and engagements of the author did not permit of the addition of 

 a descriptive text. Full explanations, however, accompany each plate. 



Bacteria-like Bodies in Tissues and Ova. §— Herr J. Blochmann has 

 studied the occurrence of bacteria-like bodies in the tissues and eggs of 

 various insects, e.g. in Periplaneta orientalis and Blatta germanica. 

 In the central cells of the fatty body, in the ova, and in the embryos 

 these curious elements were abundantly found. They occur in other 

 animals besides insects, and closely resemble the bacteroids noted in the 

 roots of Leguminosfe. Leuckart observed similar bodies, which he was 

 inclined to regard as parasitic, under the cuticle of Distomum cercarise. 

 Schneider observed similar structures in Mesostomum. F. E. Schulze 

 suggested that similar structures in Pelomyxa were symbiotic Bacteria, 

 or perhaps reserve accumulations. Korschelt noted the appearance of 

 small strongly refractive granules in the yolk-grains of bug ova. 

 Zacharias and Van Beneden have observed similar elements in the ova of 

 Ascaris megalocephala. They grow and divide, and are to be regarded 

 as primitive granules. Altmann has also described their physio-chemical 

 import. 



* Arch. f. d. Gesammt. Physiol. (Pfluger), xli. (1887) pp. 240-56. 

 t Arch. Sci. Phys. ct Nat., xviii. (1887) pp. 433-6. 

 X Mem. Acad. Sci. Bologna, vi. (1885) pp. 45-72 (12 pis.). 



§ Biol. Centralbl., vii. (1887) pp. 606-8. Versamml. Deutsch. Naturf. u. Aerzte, 

 Wiesbaden, 1887. 



