48 BOTANICAL GAZETTE [JULY 
zygote, ‘‘a fresh phase having thus been gradually interpolated,” 
in other words, that its origin is antithetic. It would seem that 
in his opinion the sporophyte has probably appeared in just one 
way. This does not mean that all sporophyte plants are homo- 
genetic, but that all have had an origin similar to that of the sporo- 
gonium of bryophytes. Professor Bower acknowledges that 
the present tendency is toward a comprehensive polyphyletic — 
view as regards alternation, stating that “when difficulties arise 
refuge is taken in the plausible suggestion of distinct lines of 
descent.” 
Dr. Lang’s paper is rather a presentation of current views 
than an expression of opinion in reference to any of them. He 
recognizes the fact that the regularity of the zygote product 
in such forms as CEdogonium and Coleochzte represents a life 
history decidedly different from the homologous alternation of 
sexual and asexual plants in most thallophytes. From one point 
of view this zygote product is merely a reduced asexual indi- 
vidual; from another point of view it is not a reduced asexual 
individual, but a special adaptation to multiply the product of 
fertilization. The former is the theory of homologous origin: 
the latter the theory of antithetic origin. Certainly the facts 
of morphology do not decide which theory is correct. Dr 
Lang calls attention to the fact that in considering alterna 
tion the possible polyphyletic origin of the archegoniates must 
be kept in mind, as the pteridophytes may represent an entirely 
distinct line from the bryophytes, as suggested by Goebel. 
In spite of Professor Bower’s disposition of apogamy as 4 
argument, Dr. Lang thinks that experiments with this phenome — 
non indicate so clearly that the gametophyte may assume char- 
acters of the sporophyte under suitable conditions, almost # 
complete series of transitions between gametophyte and spor” 
phyte having been observed, that such a general property of the 
fern gametophyte cannot be disregarded in the discussion, evel 
though the phenomenon may be called teratological. He thinks 
that apogamy Suggests the homology of the gametophyte and 
sporophyte, and may suggest how pteridophytes could have 
