Class ijicatioii . 149 



processes to be described may be termed tlie suiiphj- 

 ing gamete (abgebende Gamete), lias usually a round 

 and larger body, but shows no otlier apparent differ- 

 ence before contact with the other {a), the receptive 

 gamete (aufnehmende Gamete). The latter usually 

 continues to be smaller, and often very small, and 

 puts out rhizoid branches, and if one of these, after 

 longer or shorter growth, encounters a supplying 

 g-amete it applies its extremity to it as a conjugating 

 tube (s), and increases in thickness, while it ceases to 

 grow in length. The mem.brane between the con- 

 jugating tube and the supplying gamete disappears 

 at the point of attachment, and an open communica- 

 tion between them being thus established, the whole 

 of the united protoplasm of both gametes passes into 

 an enlargement of the conjugation-tube, close to the 

 point of attachment ; the swelling gradually expands 

 into a spherical vesicle, and, being delimited by a 

 membrane after receiving the protoplasm, becomes a 

 thick-walled zygospore (E, s). The outer wall of 

 the zygospore assumes a pale yellow colour, and in 

 some cases continues smooth, in others is covered with 

 short spikes, which begin to form at the same time as 

 the enlargement in the tube. The whole process of 

 forming a zygospore, from the attachment of the 

 conjugating-tube and the maturation of the zygospore, 

 was completed, in the case observed by Nowakowski, 

 in about 6 — 7 hours. A few instances are known of 

 the conjugation of 2 — 3 receptive with one supplying 

 gamete, and of the consequent formation of 2 — 8 

 zygospores. The zygospore, as has been already 

 said, is a resting-spore. It germinates when its 



