BOOKS AND CURRENT LITERATURE 



Recent Work on the Life Histories of the Kelps. — Since 

 Drew's announcement^ that the motile cells of Laminaria are actually 

 gametes, and not zoospores, as they were previously considered, there 

 has been a good deal of skepticism as to the accuracy of his observations. 

 Recent papers by Sauvageau" and Kylin^ have cleared the matter up 

 in a most interesting way. To Sauvageau belongs the credit of priority. 

 Kylin's results, however, confirm and add somewhat to the earlier 

 observations. 



The facts as given by Kylin may be summarized as follows. On 

 germination, the zoospores give rise in three to five weeks to gameto- 

 phytes. The male gametophytes are short, monosiphonous, and 

 irregularly branching. They produce antheridia singly as small 

 terminal or lateral cells. The antherozoids have not been observed. 

 The female gametophytes may be similar to the male but with fewer 

 and larger cells, or may consist of a single large cell produced from the 

 swelling gerin tube of the germinating zoospore. Li either case all 

 cells of the female gametophytes are oogonia, each producing a single 

 egg, which is extruded from a narrowed terminal neck. Fertilization 

 was not observed. The (fertilized) egg develops directly into an 

 unbranched sporophyte (the Laminaria plant), which is at first mono- 

 siphonous and later becomes a flattened plate. By the end of the 

 first summer the young sporophyte is 2 to 3 dcm. long. Cytological 

 details are entirely lacking. It is to be expected that these will soon 

 be forthcoming. 



^ Drew, G. H. The -Reproduction and Early Development of Laminaria 

 digitata and Laminaria saccharina. Ann. Bot. 24. 1910. 



- Sauvageau, C. Sur la sexualite heterogamique d'une Laminaire {Saccorhiza 

 bulbosa). Sur les debuts du dcveloppement d'une Laminaire {Saccorhiza bulbosa.) 

 Compt. rend, de I'acad. sci. Paris 161. 1915. 



Sur les gametophytes de deux Laminaires (L. flexicaulis et L. Sac- 

 charina). Ibid. 162. 191G. 



Sur la sexualite heterogamique d'une Laminaire (Alaria esculenta). 



Ibid. 162. 1916. 



^ Kylin, H. Ueber den Gencrationswechsel bei Laminaria digitata. Svensk. 

 bot. Tidskr. 10, 551-561. 1916. 



190 



