28 
that of two daughter nuclei, lying in the same cell and being 
under the same conditions, only one should divide. Fig. 4 B/, 
BBe and BBB are only inserted to make the scheme cover all 
possibilities. 
Two megaspores are formed (Type C). 
One sole division, in which cellwall-formation is omitted, 
both ro nape thus being involved in the same cell. Either 
one (fig. 4 Ca) or both (fig. 4 CC) may develop. 
Though megaspore-formation has been described in very many 
cases, it is still impossible to produce a more or less complete 
list of the various types. First of all only comparatively few 
records, according to Courter and Cuamperuain (1912, p. 76), 
can be accepted without reserve, even regarding the number 
of megaspores formed! Secondly in almost all publications va- 
cuolation is wholly left out of discussion, the figures being often 
too scanty to allow any conclusion as to the megaspore-type. 
Theretore all attempts at compiling a complete list have been 
given up. The following artificial scheme however furnishes a 
serviceable survey of all possibilities and of a few necessary 
instances to illustrate them. 
| Monosp. sacs 
Bispor. sacs Trisp, sacs | Tetrasp. sacs 
4 megaspores formed 
normal walls | Type A | 
the “normal 
| type” | 
only 1st. div. Type Az | Type AA 
walls | Calopogon Smilacina 
(Pace 1909) | (Mc. ALLISTER 
1909, 1914) 
no walls Type Ay Type AAg Type AAA Type AAAA 
Clintonia Peperomia 
(Smit 1941) (Jounson 1914) 
Avena (Can- é Penaeaceae 
Non 1900) | (SrepHENs 1909) 
