88 GENETICS [Bot. Absts. 



appeared and fruit bodies were produced. The chief method of bringing about the plasmog- 

 amy is through the union of a hyphal cell of one thallus with an oidium from another thallus. 

 Miss Bensaude concludes that the "dicaryo" in C . fimentarius is formed following plasmogamy 

 between cells coming from two different thalli.— The transformation of a primary mycelium 

 into a secondary mycelium is very difficult to observe. This is brought about by the anasto- 

 mosis of 2 hyphal cells of different thalli in C. fimentarius. The fusion of 2 such cells (plas- 

 mogamy or pseudogamy) introduces the cytoplasm and nucleus or nuclei of one cell into the 

 other, which results in the establishment of a binucleate cell. If 2 cells unite which have more 

 than 2 nuclei in common, all disintegrate but 2. The uninucleate oidium may fuse with a 

 hyphal cell, and this is a very common means of bringing about the initial binucleate condi- 

 tion of the cell. — Each cell in these secondary hyphae is binucleate, constituting a "dicaryon." 

 Conjugate nuclear division occurs in these hyphae as a rule in the apical cell, although inter- 

 calary cells divide occasionally. At the time of division the 2 nuclei move to the middle of 

 the cell, and the actual process of cell division is preceded by the formation of a protuberance 

 which is to form a clamp. One of the nuclei which Miss Bensaude calls (+) on the basis of 

 her results with single spore cultures, enters this very short branch, and the (— ) nucleus 

 remains at about the same level in the mother cell. Spindles are formed and conj ugate nuclear 

 division takes place. One of the (+) daughter nuclei goes back into the mother cell, and the 

 other goes to the apex of the young clamp. A cross-wall cuts off the beak cell from the mother 

 cell. Of the 2 (—) daughter nuclei, one goes to the apical part of the mother cell and the other 

 to the basal part, and a cross-wall is formed at the level of the young clamp, dividing the cell 

 into an apical portion with (+) and (— ) daughter nuclei and a basal cell with only the (— ) 

 daughter nucleus. The little beak now fuses with the basal cell, and its nucleus passes into 

 this cell, so that it also becomes binucleate. Very often the apex of the beak fuses with the 

 mother cell before nuclear division takes place. — Reversion of secondary to primary mycelium 

 occurs, in which case a uninucleate cell appears among binucleate cells. No clamps are 

 found on the cross-walls of this cell, and these uninucleate cells may bear oidia." [Through 

 rev. in Bot. Gaz. 68 : 67-68. July, 1919.] See also Bot. Absts. 3. Entries 347 and 644.— Michael 

 Levine. 



598. Botjlenger, G. A. L'evolution est-elle reversible? Considerations au sujet de cer- 

 tains poissons. [Is evolution reversible? Considerations relating to certain fishes.] Compt. 

 Rend. Acad. Sci. Paris 168: 41-44. 1919. — Conclusions regarding relationships of groups have 

 often rested on belief that evolution never reverses itself. Author believes such reverses have 

 occurred. In fishes of family Cichlidae primitive teeth were undoubtedly conical. Many 

 African members have bi- or tri-cuspid teeth, and in some of them conical and bi- or tri-cuspid 

 mixed. Young fishes, however, have bi- or tri-cuspid teeth, older ones conical, indicating 

 that evolutionary trend is now back toward conical shape. Concludes also that in evolution 

 of this family the number of vertebrae was reduced to about 24, but subsequently increased 

 to 30 or more in African forms whose dentition is aberrant, thus constituting another rever- 

 sal. Other more obscure evidences of reversal of evolution are found in same family. — A. 

 Franklin Shull. 



599. Botjlenger, G. A. Un cas d' evolution ontogenique a rebours chez un lezard africain 

 (Eremias lugubris A. Smith). [A case of reversed ontogenetic evolution in an African lizard.] 

 Compt. Rend. Acad. Sci. Paris 168: 78-80. 1919. — These lizards descended from striped 

 ancestors, and adults are striped at present. Some young, however, show stripes broken up 

 into spots, which later elongate and unite to form stripes. Is regarded as case of reversed 

 ontogeny. Author speculates also concerning purpose of jet black and bright color-pattern 

 of young, as compared with gray and pale yellowjand tan of adult, so similar to desert regions, 

 but reaches no conclusion. — A. Franklin Shull. 



600. Boveri,Theodor. Zwei Fehlerquellen bei Merogonieversuchen und die Entwick- 

 lungsf ahigkeit merogonischer und partiellmerogonischer Seeigelbastarde. [Two sources of error 

 in investigations of merogony and the ability of merogonic and partially merogonic sea-urchin 

 hybrids to develop. Arch. Entwicklungsmech. Organ. 44: 417-471. 3 pi. 1918. — Unfinished 



