RECENT ADVANCES IN SCIENCE 61 



in which, unlike plants, the individuals can migrate from 

 place to place and so substitute for a stress resulting from 

 over-population an environmental stress caused by a new set 

 of climatic or physiographic conditions." 



Four papers deal with the nuclear apparatus from more or 

 less general points of view. " The Period of Synapsis in the 

 Egg of the White Rat, Mus norvegicus albinus," by Pratt and 

 Long; "The Synapsis and Chromosome Organisation in 

 Chorthippus (Stenobothrus) curtipennis and Trimerotrops suffusa 

 (Orthoptera)," by Wenrich ; "The Multiple Chromosomes of 

 Hesperotettix and Mermiria (Orthoptera)," by McClung, and 

 " Multiple Complexes in the Alimentary Canal oiCulex pipiens," 

 by Holt (all in Journ. of Morph. vol. xxix. Sept. 191 7). The 

 first two add to the already considerable literature on Synapsis. 

 The first concerns the phenomenon in a mammal on which 

 group but little has been previously done, but with this these 

 results are in agreement. The second, an extension of the 

 author's previous work, is also corroborative of the main points 

 already known, but some further points of detail are elucidated. 

 The third, too, is an extension of the writer's previous work on 

 an unusual condition in the chromosome complex in orthopteran 

 spermatocytes. It includes the study of a large series of speci- 

 mens of different species and reveals a close relationship be- 

 tween cytological characters and taxonomic grouping. The 

 last records that a considerable increase in the number of 

 chromosomes in the cells of the pupal intestine takes place 

 during metamorphosis. The process, moreover, is not accidental 

 since it occurs in all cells before they disintegrate, and can 

 hardly be regarded as a degeneration phenomenon owing to 

 its uniformity and regular occurrence. Its meaning is not 

 obvious. 



Other papers include : " Zellen und Plasmodien : Eine 

 kritische Studie," by Schaxel {Z00L Jahrb. 191 7) ; " Further 

 Observations on the Effects of Alcohol on White Mice," by 

 Nice (Amer. Naturalist, Oct. 191 7) ; " Genetics versus Palaeon- 

 tology," by Gregory (ibid.) ; " Linked Quantitative Characters 

 in Wheat Crosses," by Freeman (ibid. Nov. 191 7) ; "On Rever- 

 sible Transformability of Allelomorphs," by Teras (ibid.) ; 

 and " Some Observations upon Concealment by the Apparent 

 Disruption of a Surface in a Plane at Right Angles to the 

 Surface," by Mottram (Proc. Zool. Soc. Nov. 1917). 



