tort] BROW N—LACHNEA SCUTELLATA 301 
It seems probable that the ascogonium in some of the ancestors 
of Lachnea scutellata was fertilized, and that this ended the gameto- 
phytic phase and initiated the sporophytic, which ended in the 
production of spores. According to the interpretation usually 
applied to .the delayed nuclear fusion in the rusts, the above 
interpretation would hold even if nuclear fusion was delayed, as 
CLAUSSEN (8) claims to be the case in Pyronema confluens, until the 
formation of the ascus. 
From a phylogenetic standpoint, it would seem reasonable, 
therefore, in the case of Lachnea scutellata to regard the stages from 
the spore to the ascogonium as gametophytic, and those from the 
formation of the ascogenous hyphae to the production of spores 
as sporophytic. The diploid number of chromosomes exists, how- 
ever, only in primary nucleus of the ascus. Even if we should 
adopt DANGEARD’s (10) interpretation, and regard the ascus as an 
oogonium, the third division in the ascus, which shows the haploid 
number of chromosomes, would still appear to belong to the 
sporophyte. It would seem advisable, therefore, in the case of 
Lachnea scutellata, as in those previously mentioned, to distinguish 
between the alternation of generations and the alternation of the 
haploid and diploid number of chromosomes. The gametophyte 
is usually regarded as beginning with the spore mother cell, but if 
the ideas brought forward here are correct, this can hardly be the 
case in Coleochaete or Lachnea scutellata, and it would seem better 
to think of it as beginning with the spore. 
Summary 
The mature ascocarp of Lachnea is disk-shaped. The hymenium 
forms the upper surface, while the rim and lower surface are 
covered by a thick-walled cortical layer. The center is composed 
of rather loosely interlacing hyphae. 
The ascogonium is the penultimate cell of a row of about nine. 
The ascogonium is early surrounded by vegetative hyphae, the 
outer of which form the first part of the cortex, while those around 
the ascogonium remain active and give rise on one side to more of 
the cortex and on the other to hyphae which will produce pa- 
raphyses. When a part of the cortex is once formed, the develop- 
