No. 1, July, 1920] MORPHOLOGY AND TAXONOMY, ALGAE 1 57 



1014. CHXJBCH, A. II. Historical review of the Florldeae.— I. Jour. Botany 87:207 804. 

 1919. — The history of the Florideae is in its early stage bound up with that of other marine 

 plants, as out lined in the author's previous paper (.lour. Hot. 57: 205. L010) on the history of 

 the Phaeophyceae. — The separation of the group under this Bpecial name wu made by Lamou- 



roux (1813). Eleven genera were treated by him under this head. Color was largely UBS 



a distinguishing feature and thus the separations were not wholly natural. A li-' is given of 



the principal contributors and the genera later Darned after them. < )f the early colled 

 Kiitzing (1843) alone incorporated some details of modern morphology and physiology, thus 

 exhibiting a transition to the modern era. Beyond what may be termed the bookkeeping of 

 the subject, the great advances in our knowdedge especially of life histories, are due to rel- 

 atively few workers. In this connection certain papers stand out as marking epochs. (1) 

 Researches of Bornet and Thuret (1S67) on sexual reproduction, significance of sexuality, and 

 the nature of the reproductive organs. Very accurate and beautiful aquatint plates by Rio- 

 creaux accompanied this work. (2) Researches of Schmitz (1883) dealing especially with the 

 cystocarp and the nature of the cell-fusions, and with a regrouping of families and genera in 

 accordance with the nature of these reproductive phenomena. Schmitz attempted to establish 

 a double fertilization wdiich has not been sustained by later work, but his classification is the 

 basis of the one now in use. (3) Researches of Oltmanns (1898) who succeeded in explaining 

 the nature of the secondary fusions. These peculiar phenomena were explained as solely an 

 attempt to obtain food-supplies for the parasitic generation. (4) Researches of Yamanouchi 

 (1906) which stand as a model of careful work on the cytology of reproduction in this group. 

 The cytological relations of the different individuals in the trimorphic sequence in the life- 

 cycle were clearly established by him. More recently Svedelius, Kylin and Cleland have 

 shown that the haploid and diploid nuclear phases may not conform to the morphological alter- 

 nation of gametophyte and sporophyte, which may aid in freeing botany from the curious 

 obsession, dating from Strasburger, that cytological phenomena can be a causal factor in 

 the differentiation of the life cycle. (5) Within the present generation the Florideae share 

 in the new outlook under the heading ecology. — K. M. Wiegand. 



1015. Church, A. H. The plankton-phase and plankton-rate. Jour. Bot. 57: Supplem. 

 III. 1-S. 1919— See Bot. Absts. 4, Entry 182. 



1016. Cleland, Ralph E. The cytology and life-history of Nemalion multifidum, Ag. 

 Ann. Botany 33: 323-351. PI. 22-24, 3 fig. 1919.— Author finds a true pyrenoid in the center 

 of the radiating chromatophore, its prominence being directly proportionate to its oppor- 

 tunities for photosynthetic activity. The substance of the pyrenoid breaks down readily 

 under inferior fixation but is well preserved and stains deeply after fixation with chrom- 

 osmo-acetic acid. The product of photosynthesis is a soluble "Floridean starch" which lies 

 diffused throughout the cytoplasm of the cell and stains wine red to violet with iodine. — 

 When the spermatium escapes from the antheridium its nucleus is in prophase of mitosis and 

 this division is completed after its attachment to the trichogyne. The spermatium there- 

 fore becomes binucleate and is the homologue of an antheridium. Several male nuclei may 

 pass into the trichogyne but only one enters the carpogonium. A trichogyne nucleus is only 

 occasionally formed and, when present, quickly breaks dow r n, the fusion of gamete nuclei 

 involves a fusion of chromatic nucleoles. The first mitosis of the zygote nucleus takes place 

 at once and is a reduction division. During early prophase of this mitosis a delicate reticu- 

 lum is formed the threads of which take on a parallel arrangement, apparently fusing, thicken, 

 shorten and thus by condensation form 8 bivalent chromosomes. These are later differen- 

 tiated as eight pairs of chromosomes distributed about the nuclear cavity in a clear stage of 

 diakinesis. The 16 chromosomes of this diploid group are therefore segregated at once by 

 this reduction division in the zygote. Following the reduction division in the fertilized 

 carpogonium, a cell is cut off below containing one of the tw r o daughter nuclei and there is 

 occasionally a mitosis in this cell, but this is the nearest approach to the formation of a tetrad 

 group such as is reported in Scinaia. The haploid chromosome number, eight, is present in all 



