PHYCOMYCETES 



247 



have been exhausted by the rhizoids. When it has reached 

 a certain size, varying according to the food which has 

 been supplied to it, it shows itself in many specimens to be 

 a sporangium, or, if the term is preferred, a prosporangium. 

 It grows out at one spot into a bluntly and irregularly 

 cylindrical, thick tube, with a delicate membrane, into 

 which the whole of the protoplasm passes, and is at once 

 divided into swarmspores. This process of development 

 may be repeated for many generations, and leads to an 

 immense multiplication of individuals, if there is a sufficient 

 number of Euglenae within reach. When this has taken 

 place, the course of events changes. The young plants 

 remain for the most part small, and become gametes which 

 conjugate in pairs, each pair forming a zygospore, and 

 these behave as resting-spores. The two conjugating 

 gametes of a pair hare no definite position or distance 

 with respect to one another, and. are similar in form to the 

 non-conjugating plants. The one which from the processes 

 to be described may be termed the supplying gamete (abge- 

 bende gamete) [male organ] has usually a round and larger 

 body, but shows no other apparent difference before 

 contact with the other, the receptive gamete (aufnehmende 

 gamete) [female organ]. 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 [male] gamete, it applies its 

 extremity to it as a conjugating tube, and increases in 

 thickness, while it ceases to grow in length. The mem- 

 brane between the conjugating tube and the supplying 

 gamete disappears at the point of attachment, and an open 

 communication between them being thus established, the 

 whole of the united protoplasm of both gametes passes 



