

i^] CURRENT LITERATURE 247 



cytoplasm some process which is symbolized by the pairing of chromosomes in 

 synapsis, and which, owing to differences in the composition of the parental idio- 

 plasms, leads to derangement and finally cessation of the metabolism that had 

 previously been carried on successfully. Some such hypothesis is necessary to 



germ cell formation 



necessity 

 produced 



Tischler agrees with Jost that the increased luxuriance of some hybnds is 

 bably due to a "poisoning" effect of one species on the other. Some of the 



cases 



Three classes of facts are cited to show that there is not a segregation of charac- 

 ters during reduction in Mendelian hybrids: (1) Cases of vegetative splitting, 

 as in Syringa correlate and Cytisus Adami. (2) Certain cases of latency or cryp- 

 tomery (Tschermak); e. g., the crossing of two white forms having certain other 

 characters gives a violet hybrid. But such cases have been otherwise explained 

 by the Mendelians. (3) Characters mendelize which cannot be represented by 

 distinct portions of the idioplasm. Here are cited annual and biennial races of 

 Hyoscyamus niger, immunity and non-immunity to rust in certain grains, and 

 sterility and non-sterility in Lathyrus. On the other hand, it might be said that 

 if the chromosomes are unlike, then each must represent some general property 

 of the whole organism, if it represents anything. Tischler concludes that in 

 the reduction divisions there is not a true segregation but latescence (Latentwerden) 

 of characters. It is questionable whether this is an improvement over the idea 

 of chromosomes or representative particles in the dominant and recessive con- 

 dition in the germ cells, a hypothesis which will undoubtedly have to be given 

 up- Drosera rotundifolia X longifolia produces pollen grains in tetrads, and in 



characters belonging to each parent. This 



cases 



indicates a splitting of characters during reduction. But Bateson crossed races 



rus 



pos 



and toe F * gave long: short in the ratio 3: 1. From this it appears that it u 

 a °le to have Mendelian behavior without segregation of characters during 

 eduction. 



similar 



The frequent sterility in mutants, accompanied by 

 foose in hybrids during reduction, as the reviewer has shown, 8 Tischler 



ascribes 



R. R. Gates. 



Temperature and growth.-Beginners in research will do well to study his 

 P^ by Balls.' It is f a type really too rare. It shows how a keen scientific 

 ^emment is alert to appreciate the significance of a casual observation m its 

 ^"ng upon a fundamental problem. It shows how difficulties may be overcome 



8 Gates, R. r., Pollen deveIopment in hybri ds of Oenothera lataXO. Lamarckiana, 

 lts Nation to mutation. Box. Gazette 43 :«i-"5« P ls - *~+ I9 ° 7 " 



W., Temperature and growth. Annals of Botany «: 5 57- 



"^ls, Lawrence 

 908. 



