March 7, 1913] 



SCIENCE 



385 



the multi-seriate condition longer than the adja- 

 cent part, where traeheid is in contact with 

 traeheid. This is a contrast to some of the Abie- 

 tinese where tlie ray pitting consists of ' ' Gross- 

 eiporen ' ' derived from the fusion of smaller pits. 



Both leaf traces and pitting are considered as 

 indicating the Cordaitalean connection of the 

 Araucarinese and as directly opposed to the deriva- 

 tion of the AraucarineK from the Abietineae. The 

 anatomical evidence is thus in accord with the 

 geological, since, as has been recently shown, the 

 forms of the older strata which were thought to 

 have been Abietinean have proved not to be 

 authentic. 

 Macrosamia Moorei, a Conneciing Link between 



Living and Fossil Cycads: C. J. Chamberlain, 



University of Chicago. 

 A Possible Means of Identifying the Sex of + 



and — Strains in the Mucors: A. F. Blakeslee, 



Carnegie Institution. 



Certain of the hermaphroditic species of the 

 mucors are distinctly heterogamic, forming regu- 

 larly large female gametes and smaller male 

 gametes. By growing the ( + ) and ( — ) races of 

 an isogamous dioecious species in contrast with 

 such an heterogamic hermaphroditic species, a 

 sexual reaction has been found to occur between 

 female branches of the hermaphrodite and 

 branches of the ( — ) race, on the one hand, and 

 between male branches of the hermaphrodite and 

 branches of the (-+-) race on the other hand. This 

 reaction would lead one to consider the ( — ) race 

 male and the ( + ) race female. 

 A Suggestion as to the Phylogeny of the Asco- 



myeetes: Ernst A. Bessey, Michigan Agricul- 

 tural College. 



Of the two suggested points of origin of the 

 Ascomycetes, the Phycomycetes are excluded in 

 view of their non-septate plant body and the sim- 

 plicity of the structures resulting from the sexual 

 union. Many of the red seaweeds, on the other 

 hand, have a plant body in many respects similar 

 to that of the Ascomycetes, i. e., septate with a 

 single rather large pit or pore in the septum, the 

 segments being in both groups either uni- or 

 plurinucleate. In both groups, the result of the 

 sexual union is a " spore fruit, ' ' i. e., a more or 

 less extensive mass of branches from the female 

 cell terminating in the reproductive cells. The 

 fact that a number of red seaweeds are known 

 which lack chlorophyll and are strictly parasitic 

 upon other algte (red seaweeds), very often sur- 

 rounding and separating the cells of the host in 



a manner similar to that shown by the lichens with 

 reference to their hosts and the fact that in the 

 reproduction of the latter group, e. g., Collema, 

 the male elements are, as in the red seaweeds, non- 

 motile sperm cells, suggests that lichens may 

 represent a group derived from some of the more 

 primitive red seaweeds, probably inhabitants of 

 fresh water, that became parasitic upon colonies 

 of Nostoc or other algas and gradually assumed 

 the terrestrial habit. The apothecium would cor- 

 respond to the cystocarp and the ascus would 

 phylogenetieally have some relation to the carpo- 

 spore. From such lichens have been derived then 

 the non-lichen Discomycetes, on the one hand, and 

 perhaps through the closing and becoming more 

 firm of the apothecium, may have arisen the 

 Pyrenomycetes. Similarly the teliospores of the 

 rusts and smuts would be homologous to the 

 carpospore. 



Morphogenesis in Fediastrum: B. A. Harper, 



Columbia University. 



In the genus Fediastrum we find all degrees of 

 variation in cell differentiation from species in 

 which the colonies are composed of cells which are 

 practically all alike to others in which only the 

 peripheral cells are provided with well-developed 

 spines, while in the central region the spinous pro- 

 jections are only slightly indicated by the kidney- 

 shaped form of the cells with the reentering angle 

 on the outer side. In the species with uniform 

 cells these may show either very long spinous 

 processes or almost none at all. The reproduction 

 of the colonies by motile zoospores, which after 

 swarming for from five to fifteen minutes arrange 

 themselves spontaneously in the plate-shaped new 

 colony shows that as in Eydrodictyan the form of 

 the colony is not predetermined by any spatially 

 differentiated representation of the adult in the 

 organization of the germ plasm. The cells arrange 

 themselves in accordance with the principle of 

 least surfaces modified by their specifically in- 

 herited cell form and the law of reproduction by 

 bipartition. All the cells of a given species are in 

 general alike in their inherited form and capaci- 

 ties for differentiated growth, and are totipotent. 

 The differentiation between cells in species which 

 show it is due to cellular interaction in the forma- 

 tion and growth of the colony. This morpho- 

 genetic equivalence of the cells is most clearly 

 shown in cases in which the cells are abnormally 

 or unusually situated as a result of unfavorable 

 environmental conditions. All the species share 

 an inherited tendency to produce one or two spines 



