Insect development. II. Mitotic activity in the grasshopper embryo

✍ Scribed by Eleanor H. Slifer

• Publisher: John Wiley and Sons
• Year: 1931
• Tongue: English
• Weight: 261 KB
• Volume: 51
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1050510210

✦ Synopsis

Abstract

The onset of hibernation in Melanoplus differentialis eggs kept at high temperatures is accompanied by a fairly abrupt cessation of cell division. The total number of mitotic figures present in the different individuals of a series of embryos of this grasshopper, from eggs kept for eighteen to twenty days at 25°C. from the time of saying, was found to vary between 1000 and 4400. In contrast to the conditions found in eggs of this age, embryos from eggs kept twenty‐seven days at 25°C., as well as those older and still in the hibernating state, contained few or no dividing cells. During the course of the work it was found that, in rare cases, hibernation failed to occur, a few or many of the eggs developed without a pause when kept at 25°C., and hatched at approximately the thirty‐eighth day. The detection of variations in the rate of mitotic activity over short periods, as originally planned, was found impossible, because of the comparatively small number of embryos used.