BLAST0CLAD1ALES 621 



deliquesce to form pores through which the planonts emerge (Fig. 42 A-B, 

 p. 626). Emerson (1941) states that the whole process of germination 

 may take place within an hour if environmental conditions are favorable. 



The cytological sequence of events in the maturation and germination 

 of the resting spore was followed by Wilson (1952). He discovered that 

 certain internal changes apparently determine maturity and capacity 

 for germination and that, in fact, such changes must occur before the 

 latter process can take place. 



Young resistant sporangia soon after delimitation possess a clear 

 homogeneous protoplasm, nonstainable with aceto-orcein. Concurrent 

 with the thickening, pitting, and pigmentation of the wall, spherical 

 bodies appear which take this stain. These "chromospheres" persist 

 until near the end of the maturation period, when the diploid nuclei 

 enter the prophase of Meiosis I, at which time they become eroded and 

 disintegrate. The spore is now mature. The interval during which 

 chromospheres exist corresponds to the maturation period. Their dis- 

 appearance signals the changes that make germination possible. 



External conditions also affect germination. For example, Wilson 

 found that temperatures of 20 to 25 degrees C. produced most uniform 

 germination. In some species meiosis is an integral part of germination 

 and metaphases of Meiosis I were abundant 55 to 65 minutes after 

 resting spores were placed in water. Metaphases of Meiosis II appeared 

 in 80 to 110 minutes and after two hours the haploid planonts escaped. 

 Time for germination varied somewhat according to the temperature, 

 strain, and age of the culture. 



After the second division of meiosis, bodies resembling the aforemen- 

 tioned chromospheres were seen. They collected around the nuclei in 

 cuplike fashion and became the nuclear caps. Whether the premeiotic 

 and postmeiotic chromospheres are chemically alike is not known. 

 Wilson thinks it unlikely that they are chondriosomal in origin, since 

 they withstand strong acid solutions. He notes that such nuclear caps 

 are present only in the motile stages, which gives weight to Kusano's 

 (1912) suggestion that they are concerned with food metabolism and 

 thus are analogous to the macronucleus of the Ciliata. 



Basic haploid chromosome numbers are given by Wilson (1952) and 

 by Emerson and Wilson (1954) for the following species of Allomyces: 



