THE STRUCTURE OF THE CHROMOSOMES 



139 



and again shorten (Fig. 76, d to h). These nuclei are of interest in 

 connection with the problem of the origin of karyolymph, which is rela- 

 tively abundant here. In the opinion of de Litardiere it moves in between 

 the chromosomes during the telophase, but its exact relation to chromo- 

 somal constituents is undetermined. 



Chromonemata in Sporocytes. — The microsporocytes of certain 

 plants are favorite objects for the demonstration of chromonemata 

 because of the large size of the chromosomes and the ease with which 

 they may be treated with various reagents or examined in the living 

 condition. 10 The chromonemata stand out clearly at late prophase, 





2$a 



Fill. 77. — Photographs of chromonemata. a, sporocyte of 

 treated with hot water. (After Sakamura, 1927a.) b, sporocyte 

 anaphase /. (After Nebel, 19325.) c, sporocyte of Trillium 

 Hjiskins and S. G. Smith, unpublished.) d, salivary gland 

 Kaufm,ann.) 



Tradescantia virginica 

 of Tradescantia refiexa, 

 erectum. (From C. L. 

 of Drosophila. (From 



metaphase, and anaphase in smear preparations fixed with chrom-osmic- 

 acetic mixtures and stained with hsematoxylin (Kaufmann, Taylor) or 

 fixed with chrom-aceto-formalin and stained with crystal violet (Sax) 

 or brazilin (Belling); also in preparations in acetocarmine (Shinke), 

 neutral violet (Kuwada), or ruthenium tetroxide (Nebel). They can be 

 seen in living cells mounted in Ringer's solution (Martens), sugar solution 

 or olive oil (Sakamura) (Fig. 77). The matrix of the chromosome can 

 be dissolved away with hot water, leaving the spiral chromonemata iso- 

 lated (Sakamura). Prefixation treatments may increase their visibility 

 (Kuwada, Nebel). For the successful observation of chromonemata in 

 fresh sporocytes special attention must be given to the pH of the 



1" For accounts of chromonemata in sporocytes, see Kaufmann (1926o?)) on 

 Tradescantia and Podophyllmn; Kuwada and Sugimoto (1926), Kuwada (1927, 

 1932a6), Kuwada and Sakamura (1926), Sakamura (1927a6), Martens (1929o) and 

 Nebel (1932) on Tradescantia; Belling (19286) on Lilium; Maeda (1928, 1930a) on 

 Lathyrus; Inariyama (1928) on Hosta; Babcock and J. Clausen (1929) on Crepis; 

 Shinke (1930) on Tradescantia, Lilium, N^arcissus, and other genera; Sax (1930c) on 

 Secale and Lilium; Taylor (1931) and Tuan (1931) on Gasteria; F. H. Smith (1932) on 

 Galtonia. Binder (1927) describes them in the spermatocyte of the kangaroo. Lucas 

 and Stark (1931) photographed them with ultra-violet light in living grasshopper 

 spermatocytes. 



