No. 1, August, 1920] GENETICS 59 



with low-grade mentality than superior. This is at variance with the popular notion of the 

 close relationship between genius and insanity. — The high incidence of tuberculosis with 

 insanity often leads to mistaken inferences. — The extreme frequency of tuberculosis in the 

 total population must be remembered as well as the fact that the insane, by reason of their 

 deterioration, tend to live in conditions predisposing to the disease. — Two other students, 

 Koller and Diem, discovered thai insane aunts and uncles occur as frequent ly in families of 

 sane as of insane and that, therefore, collateral insanity is relatively unimportant unless asso- 

 ciated with parental insanity. — These studies demonstrate that our knowledge is inadequate 

 to warrant theories of neuropathic heredity and how imperative such research is. — Miriam 

 C. Gould. 



427. Nachtsheim, H. Der Mechanismus der Vererbung. [The mechanism of heredity. | 

 Naturw. Wochenschr. 18: 105-114. 1919. 



428. Nachtsheim, H. Berichtigung. [A correction.] Zeitschr. indukt. Abstamm. 

 Vererb. 20:295. 1919. 



429. Nakahara, Waro. A study on the chromosomes in the spermatogenesis of the stone- 

 fly, Perla immarginata Say, with special reference to the question of synapsis. Jour. Morphol. 

 32:509-529. PI. 1-3. 1919. — Ten chromosomes appear in the spermatogonia division. The 

 chromosome group consists of two pairs of V's, a pair of rods, two spherules (m-chromosomes), 

 and two unpaired rods, one of which is much longer than the other. These last are interpreted 

 as the X- and Y-chromosomes, respectively. Preparatory to the first spermatocytic division 

 a double spireme forms out of the resting nucleus, and this process the author interprets as 

 a precocious split for the second spermatocytic division, which follows the first without a 

 resting stage. Homologous chromosomes are connected to each other telosynaptically in 

 the spireme; later, the members of each pair bend toward each other at the synaptic point and 

 become reunited parasynaptically before the metaphase, thus forming rings and tetrads. — 

 Bertram G. Smith. 



430. Nelson*, J. C. Monomorphism in Equisetum Telmateia Ehrh. Amer. Fern Jour. 

 9: 93-94. 1919.- 



431. Nicolas, G. Variations de l'androcee du Stellaria media L. en Algerie. [Variations 

 of the androecium of Stellaria media L. in Algeria.] Bull. Soc. Hist. Nat. Afr. Nord. 9: 135-137. 

 1918. 



432. [Norstedt, C. T. O.] [Rev. of: Harms, U. Uber die Geschlectsvertheilung bei 

 Drya octopetala L. nach Beobachtungen in Kgl. Botanischen Garten Berlin-Dahlem. (Con- 

 cerning sex ratios in Drya octopetala in the Kgl. Botanical Garden Berlin-Dahlem.) Ber. 

 Deutsch. Bot. Ges. 36:292-300. Fig. 5-10. 1918.] Bot. Notiser 1918: 247. 1918. 



433. Northrop, J. II. Concerning the hereditary adaptation of organisms to higher 

 temperature. Jour. Gen. Physiol. 2: 313-31S. 1920.— The experiments described were per- 

 formed with races of Drosophila raised on sterile yeast cultures and handled with bacterio- 

 logical care to prevent the entrance of bacteria into the breeding flasks. The incubators em- 

 ployed to maintain the higher temperatures were controlled within 0.2° to 0.3°G. of the desired 

 temperatures by means of an original device regulating the flow of water through the jackets. 

 Drosophila will develop at 32.5°C. ; the rate of development increases from 10° up to 27.5°, 

 but from 27.5° the rate falls. If the higher temperature in which a fly is raised occasions a 

 lasting adaptation, it would be expected that eggs from such a fly would show increased re- 

 sistance to high temperature. It was found that flies raised at 20°C. produce eggs that are 

 capable of full development when raised in temperatures 29° and 32°C., but when raised in a 

 temperature of 33° they will not go beyond the pupal stage. Flies raised in incubators at 32° 

 produce eggs that will develop into adults when raised at 29°, but at 32° and 33° they will not 

 even form larvae. The difference in these two sets of results is not due to deleterious effects 



