ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 575 



Influence of Temperature on Development of Mealworm.* — 

 August Krogh has experimented with the pupae of Tenebrio molitor, to 

 see how the rate of development and the production of C0 2 are affected 

 by different temperatures. He finds that the relation between the 

 temperature and the rate of development cannot be expressed in terms 

 of van't Hoff's formula, but between 18*5° and 28° the relation is 

 algebraic, and the curve representing it is a straight line. Beyond these 

 limits the curve is not straight, but bends upwards at the lower tempera- 

 ture and downwards at the higher. Normal development is still possible 

 at temperatures between 15° and 33°. 



In the metabolic activity of the pupas of the mealworm three stages 

 are recognizable, corresponding roughly to periods of disintegration of 

 larval tissues, comparative rest, and formation of the tissues of the imago. 

 The metabolism in the tissue disintegration period is practically of the 

 same intensity as in the tissue formation period. The total amount of 

 COo produced during the pupal period is the same at all the tempera- 

 tures tried (21°-33°). There is no optimum temperature with regard 

 to metabolism. The relation between the temperature and the average 

 C0 2 production per hour cannot, therefore, be expressed by van't Hoff's 

 formula, but follows the same curve as that found for the rate of develop- 

 ment. The relation between the temperature and the metabolism of 

 cold-blooded animals is generally supposed to follow van't Hoff's law. 

 As the above experiments plainly show, this assumption must be received 

 with caution. 



Spermatogenesis of Mole Cricket, f — D. Voinov has made a study 

 of the spermatogenesis of Gryllotalpa vulgaris which shows an interesting 

 state of the chromosomes. The stage of multiplication of sperm-cells 

 is in May, maturation is accomplished in July, the testes usually show 

 nothing but ripe spermatozoa in August. Fifty specimens were studied 

 and they showed great uniformity. 



The resting spermatogonia show two nucleoli and a weak reticulum 

 of linin with a very small number of chromatic granulations. The 

 nucleoli are partly chromatic, partly plasmic. They are micro-chromo- 

 somes in Wilson's sense, and combine at the beginning of the prophasis 

 to form a bivalent micro-chromosome, characteristic of the equatorial 

 plate of the spermatogonia. After the mitosis they separate again and 

 resume the aspect characteristic of the resting stage. 



The ecpiatorial spermatogonial plate shows fifteen univalent chromo- 

 somes, so with the bivalent micro-chromosome there are seventeen, which 

 include twelve autosomes, a large and a small idiochromosome, and an 

 accessory chromosome. Thus Gryllotalpa is one of the rare forms with 

 three special types of chromosomes — micro-chromosomes, idiochromo- 

 somes and an accessory chromosome. It is also marked by the way in 

 which the reduction from seventeen diploid chromosomes to seven 

 haploid chromosomes is effected. All the spermatids have seven chromo- 

 somes, but there are four different categories, a sort of double dimorphism. 



* Zeitschr. allg. Physiol., xvi. (1914) pp. 178-90 (3 figs.), 

 t Arch. Zool. Exper., liv. (1914) pp. 439-99 (3 pis.). 



