1 78 Shiv Ram Kashyap.~The Structure and Development of 
A small prothallus may bear a single plant, but eight or ten plants on 
a prothallus are not unusual. Fig. 44 shows a prothallus bearing fifteen 
plants. The prothallus was brought into the laboratory without any plants 
on it, and all of them were produced on that part of the prothallus which 
was formed while in the laboratory. The proximity of several male plants 
Text-fig. 45. 
facilitated fertilization. It may also be mentioned that it is rare to find 
a prothallus with antheridia and a young plant growing out of it. Self- 
fertilization, therefore, does not take place, as the archegonia which were 
produced on the bisexual prothallus would be shrivelled before the an- 
theridia are ripe and no new archegonia can be produced, it appears, along 
with the antheridia. In the very few cases where a plant was found growing 
out of an antheridium-bearing prothallus the archegonium may have been 
fertilized from another prothallus. Fig. 45 shows a single plant coming out 
of a small prothallus. The plant here has already produced branches of the 
second and third order. 
