346 Cleland. — The Cytology and Life-history of 
cytological phases are borne by three distinct generations, two of which are 
morphologically homologous, while the third is morphologically antithetic 
to the other two. 
Two terms have been widely applied in treating of the subject of 
alternation of generation. These terms are 1 antithetic 5 and ‘ homologous \ 
As far as cytological alternation is concerned, it may be stated as axiomatic 
that the haploid and diploid phases in all plants bear an antithetic relation 
the one to the other. The diploid condition is new, and in no way homo- 
logous to the haploid condition. 
Since the term 4 alternation of generations \ however, includes not only 
cytological but also morphological alternation, the application of either 
term to Floridean alternation of generations is unsatisfactory, since neither 
expresses the whole truth with reference to the situation in the red algae. 
The great confusion which has arisen over the subject has been largely 
a result of attempting to apply terms coined to express the relatively 
simple conditions in the Archegoniates to the more complex situation in 
the red algae. 
It is not my purpose to offer a new terminology applying to this 
situation, but to point out the great need of such. While we may continue 
for the present to use the term { antithetic ’ as expressing a larger percent- 
age of the whole truth than does the term ‘ homologous yet we should 
bear in mind that the situation in the red algae is not strictly comparable 
to that in the Archegoniates. It is to be hoped that in the near future 
a term will be proposed which will be expressive of the whole truth with 
reference to the morphological and cytological nature of the alternation of 
generations in the red algae. 
Summary. 
1. Nemalion possesses a true pyrenoid, which appears as a densely- 
staining body in the centre of a radiating chromatophore, its prominence 
being directly proportional to its opportunities for photosynthetic activity. 
This pyrenoid is actively concerned in the elaboration of soluble ‘ Floridean 
starch ’, which stains wine-red to violet with iodine, and lies diffused 
throughout the cytoplasm of the cell. 
2. The nucleus of the spermatium is in prophase of mitosis at the time 
of the escape of the spermatium and divides after the latter has become 
attached to the trichogyne. Hence the spermatium is the homologue of an 
antheridium. 
3. Several male nuclei may pass into the trichogyne, but only one 
enters the carpogonium. 
4. A trichogyne nucleus is only occasionally formed, and, when 
present, breaks down very quickly. 
