Algae. 567 



sive nuclear and cell divisions. These spores then become arranged 

 in the form of the adult colon}'- while they are still inside the old 

 cell wall. The 5'^oung colonies are liberated by the rupture of the 

 mother cell wall. The p3'renoids in the daughter cells arise de novo 

 and not by the division of a preexisting pyrenoid. One species, T. 

 wisconshiensis, is described. It occurs floating in sluggish streams 

 and lakes; Madison, Wisconsin. 



The new alga was cultivated under different conditions to show 

 that it is a distinct genus, and not a cultural form of Scenedesmus. 



There is some similaritj^ between the 3^oung daughter cells in 

 TetradesniHs and the swarm spores in Hydrodictyon in the behavior 

 of the p3'^renoid, as in Hydrodictyon, after the swarm spores are 

 formed b}' cytoplasmic cleavage, new p^nenoids appear as small 

 redstaining bodies closch' associated with the nuclei. This is exactly 

 what takes place in Tetradesinus. Jongmans. 



Yaraanouchi, S., The Life History of Zanardinia. (Contr. HuU 

 Bot. Lab. 174. Bot. Gazette. LVI. p. 1—35. 24 Fig. PI. 1-4. 1913.) 



This paper deals with nuclear conditions in the life history of 

 Zanardinia collaris Crouan. The author studied the mitosis in the 

 vegetative cells of the gamete-producing plants, the male and female 

 gametangia, fertilization and germination of the fertilized female 

 gamete, the gerrnination of the unfertilized female gamete, the 

 mitosis in the vegetative cells of zoospore-producing plants, the for- 

 mation of zoosporangia, the segmentation of the protoplasm in the 

 zoosporangium, the germination of zoospore and the alternation of 



generation. 



The principal results are summarized as foUows: 



The nucleus of the gamete-bearing plants contains 22 chromo- 

 somes and the male and female gametes contain the same number. 



In the Union of the gametes the number is doubled, and 44 

 chromosomes appear in the fertilized sporeling, which develops 

 into the Zaiiardinia plant containing 44 chromosomes. 



The nucleus of the zoospore-producing plant contains 44 chro- 

 mosomes, and the number is reduced in zoospore formation, the 

 zoospore containing 22 chromosomes. The zoospore with the reduced 

 number of chromosomes germinates and develops into an individual 

 with 22 chromosomes. 



It is evident that the gamete-bearing plants come from zoospo- 

 res and that the zoospore-bearing plants come from fertilized game- 

 tes, so that the two generations alternate in the life histor\^ 



The female gamete of Zanardinia may germinate apogamously. 

 There is no irregularity in the mitotic process, 22 chromosomes 

 being invariably present. The individual produced shows external 

 morphological characters similar to those of the product of the fer- 

 tilized gamete, but the fate of the apogamous individual was not 

 determined. Jongmans. 



Zimmermann, C, Contribuigäo para o estudo das Diato- 

 maceas dos Estados do Brasil. (Broteria. XIII. 1915.) 



Le Pere Zimmermann infatigable, malgr^ ses devoirs, continue 

 l'etude des diatomees du Bresil, champ admirable pour un explo- 

 rateur intelligent et perseverant. 



Dans cette note il indique 24 especes de Navicula avec quelques 



