FERTILIZATION 629 



twelve were the diploid number, this would correspond exactly to the 

 condition existing in Euplotes patella and in Pleurotricha layiceolata. 

 However, Gregory believes that twelve is the haploid number and that 

 the separation of the twenty-four dumb-bells into two groups of twelve 

 each, in the first maturation division, means that this is the reduction 

 division, a condition unusual in ciliates. This interpretation is weakened 

 somewhat by the fact that twenty-four dumb-bells are formed in the 

 prophase of the second maturation division, twelve passing to each pole 

 in the anaphase. It is possible that the twenty-four dumb-bells which 

 separate into two groups of twelve each in the first maturation division 

 are actually tetrads, and that the twelve going to each pole are diads. 

 This would mean that the joining of the original granules is synaptic 

 in character and that their passing to the same pole indicates splitting, 

 or equational division. This explanation is not completely satisfying, in 

 view of the events of the second maturation division. Each of the twenty- 

 four dumb-bells which are formed in the prophase of the second division 

 would have to be derived from one granule of the first anaphase dumb- 

 bells. If that occurred, then the second maturation division would be 

 reductional; but if they are formed by the splitting of entire dumb-bells, 

 as believed by Gregory, then the second division would be equational and 

 the first would be reductional. 



Whichever interpretation is correct, one thing seems clear: in all these 

 forms the chromosomes of the first maturation division are composed 

 of a definite number of loosely associated chromomeres. It is in their 

 method of distribution that interpretations differ, and further investiga- 

 tion in this field will be welcomed by those interested in meiotic phe- 

 nomena in the Protozoa. 



No parachute stage was found by Noland (1927) in Metopus sig- 

 moides. Instead, the chromatin forms a spireme, which condenses into a 

 single large sausage-shaped "chromosome" on the spindle. This divides, 

 and one part goes to each pole. The interpretation of this condition is 

 difiicult, because of the obscurity of later stages. From the appearance 

 of the synkaria in Noland's drawings, one would judge that there are 

 two large chromosomes in some, and four in others. If two were the 

 diploid number, the four would represent splitting for fission. Then the 

 single chromosome of the first maturation division could be interpreted 

 as a synaptic pair in close union. This speculation may not be justified 



