ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 437 



warmth appears to be expended in vain. Cold appears to be necessary 

 to mature winter pupas, e.g. Thais pohjxena and Rumia luteolata kept at 

 •11° C. for part of the winter nearly all died. In contrast to winter 

 pupae killed by the absence of cold are quoted summer pupse of Selenia 

 tetralunaria and of Araschnia levana, which were kept, retarded, and 

 changed in facies, but uninjured by a low temperature, for more than 

 four months, and those of Zonosoma punctaria for more than six months. 

 Other points considered in this interesting paper are the question of the 

 transformation of single- and double-brooded types, and the alteration 

 of colour and pattern by temperature. 



Maturation of Unfertilised Eggs in Tenthredinidse.* — L. Don- 

 caster describes the maturation process and early development of par- 

 thenogenetic eggs in saw-flies. There appear to be several fundamental 

 differences from the process in bees. In the saw-flies the conjugation 

 of the polar nuclei takes place only in the male-producing species, and 

 the group of chromosomes which results ultimately disintegrates ; but 

 the fact that it commonly divides into two groups lying side by side may 

 be compared with the production of " double nuclei " in the bee. The 

 number of chromosomes in all the divisions is constant, and no trace 

 was seen of tetrads or dyads to indicate the occurrence of reduction. 

 The somatic number of chromosomes is the same (at least up to the 

 formation of the blastoderm) as the number in the polar mitoses. 



Variations of Lycaena astrarche in Britain.f — L. W. H. Harrison 

 finds that Lycama astrarche Brgstr. and the variety artaxerxes are 

 connected by transition forms. The typical form in the south of 

 England entirely resembles the Continental form, and has two genera- 

 tions annually. In the north of England, especially in Durham, there 

 are distinct varieties, and one brood in the year. They approach the 

 variety artaxerxes, and have a longer larval period. The typical form 

 is to be found on the stork's bill, the Durham variety on the rock-rose. 

 The variety salmacis predominates in Durham, and the adults show 

 sexual dimorphism, which is absent in artaxerxes, the predominating 

 variety in Scotland. Harrison's general conclusion is that L. astrarche 

 and artaxerxes are geographical varieties. 



Mendel's Laws applied to Silk- worm Crosses. :£ — Kametaro 

 Toyama finds that some of the characters of silk-worms, e.g. colours 

 of cocoons and larval markings, strictly follow Mendel's laws, while 

 others do not. As the result of crossing the disintegration of parent 

 characters takes place. Each character thus produced behaves exactly 

 like an independent character, breeding true to parents. Conversely, 

 the combination of two characters takes place, and the forms produced 

 remain constant when bred together. Bateson's theory of allelomorphs 

 is confirmed. The behaviour of a character when crossed, however, 

 depends in some degree upon the characters of its ancestors, since in one 

 case (Siamese " whites " X Siamese " yellows ") no disintegration of the 



* Quart. Journ. Micr. Sci., No. 196 (1906) pp. 561-89 (2 pis.), 

 f Bull. Soc. Lepidopt. Geneve, No. 1 (1905) pp. 30-2. See also Zool. Zentralbl., 

 xiii. (1906) p. 331-2. X Biol. Ceutralbl., xxvi. (1906) pp. 321-34. 



