1922] CURRENT LITERATURE 505 
branching, the absence of a primary tubercle, and the lack of differentiated 
tissue “‘may all be urged as more or less primitive features.” The absence 
of a suspensor the author thinks may be compensated for by the haustorial 
protuberances of the foot. The same foot structure, however, also occurs in 
certain species of Lycopodium which do develop a suspensor. The absence 
of the suspensor is also counted as a primitive feature. 
In discussing the significance of its embryogeny, which is “the simplest 
among existing pteridophytes,” the author states: ‘While not suggesting 
that T'mesipteris has actually been derived from the Anthoceros cycle of affinity, 
it is clear that the absence from the former of any such organs as root or 
cotyledon suggests that they approximate in so far as they both represent 
primitive lines of development. That the simplicity of Tmesipteris is not due 
to reduction is a belief which has greatly been strengthened by the discovery 
of the rootless and leafless Rhyniaceae. The embryogeny of Tmesipteris as 
described in the present paper makes more clear-cut the theory of the origin 
of the sporophyte of the Pteridophyta from an Anthoceros-like sporangium, 
- The only new feature to be postulated here is the extension in length 
of the shoot from an apical meristem instead of, as in Anthoceros, from an in- 
definite basal meristem, and the initial cause of the shoot-elongations might 
be set down as being the care of a subterranean mode of life by the gameto- 
phyte.”—E. A. Spessarp 
Life cycles of bacteria——L6unis” has published a comprehensive survey of 
o literature dealing with cell forms of bacteria and their significance i in relation 
Oo the life history of these organisms. The discussion is amply illustrated 
wits over 40 plates containing nearly 400 figures. 
The first section of the monograph contains a discussion of cell forms. 
The author attempts to refute the monomorphistic doctrine of Conn, Kocu, 
and their followers. It is shown that many bacteria, possibly all, are pleo- 
morphic, and that the varying cell forms often referred to as “involution” or 
“degeneration’’ forms are really different stages in the life cycles of bacteria. It is 
admitted, however, that our knowledge concerning the relationships of these 
forms is all too meager. 
In the second section reproductive organs are discussed. These are 
gonidia, regenerative bodies, exospores and endospores, arthrospores, and 
microcysts. Of these the gonidia and regenerative bodies appear to take the 
most active part in reproduction, while the other organs may represent resting 
forms. It is claimed that gonidia are common to all bacteria. The fact that 
they have not always been observed may be due to their small size and high 
motility. Regenerative bodies may be of any shape, and are produced either 
by the vegetative cell or the ‘‘symplasm.”’ 
» Léunis, F., Studies upon the life cycles of oo bacteria. Part I. Review of 
the literature, i8g6-s 1918. Mem. Nat. Acad. Sci. 16: Second memoir. pp. 252. pis. 
—$ and 1-23. 
