March 2, 1900.] 



SCIENCE. 



355 



harper's studies in cell division. 



The December number of the Annals of 

 Botany contains another of those valuable con- 

 tributions to plant cytology which have ap- 

 peared from time to time from the hand of Pro- 

 fessor Harper. He takes up in the present 

 paper the cell-division in sporangia and asci, 

 using for the former mainly the species of 

 Saprole.gnia and Achlya, with some of the Mu- 

 coraceae and Synchitriaceae, also. For the cell- 

 division of asci he has made use of his previous 

 studies in the Eryaipheae, and now adds Lachnea 

 scutellata of the Pezizaceae. His summary of 

 results is in part as follows : 



"If we compare now the methods of spore- 

 formation in the ascus and in the sporangia 

 studied, the differences in the two cases are at 

 once apparent. In the ascus, as in the higher 

 plants, the cutting out" of the daughter cell from 

 the mother cell is effected by the agency of the 

 same fibrous kinoplasmic elements as were con- 

 cerned in the division of the nucleus. In the 

 higher plants the flat cell-plate is formed by 

 the ' cone-principal ' of the karyokinetic figure 

 as named by Van Beneden, while in the ascus 

 the daughter cell is cut out of the protoplasm 

 of the mother cell by an ellipsoidal cell plate 

 formed from the fibers of the antipodal cone. 

 In this process the daughter cell is cut out of 

 the interior of the protoplasm of the mother 

 cell, so that it remains surrounded on all sides 

 by the material of the mother cell. The daugh- 

 ter cells do not contain all the protoplasm of 

 the mother cell, a considerable mass remaining 

 as the so-called epiplasm. This is typical free 

 cell-formation, as I have pointed out before. 

 In all the sporangia studied, the cleavage is 

 from the surface of the protoplasm, or from the 

 surface of vacuoles of the mother cell. The 

 daughter cells are thus separated by cleavage- 

 furrows, and the nature of the division from 

 the surface inwards precludes the possibility of 

 the formation of an epiplasm. * * * 



"If we consider now the bearing of the ob- 

 servations presented, on the doctrine that the 

 ascus is a more highly developed and special- 

 ized modification of the sporangium of the 

 Zygomycetes, it is plain that the very different 

 methods of cleavage in the two cases are op- 

 posed to the assumption of any close relation- 



ship between them. In fact, it seems rather 

 difficult to imagine any intermediate stages 

 which could connect the process of cleavage by 

 surface-furrows, as seen in the sporangium, 

 with the free cell-formation of the ascus. * * * 

 "The total dissimilarity of the process of 

 cleavage in the sporangia described and the 

 ascus as I have shown it in the above account, 

 makes it necessary to look for the ancestors of 

 the Ascomycetes elsewhere than in the lower 

 Fungi. Thaxter's studies of the Laboulbenia- 

 ceae have emphasized greatly the resemblance 

 of that group to theFlorideae and the hypothe- 

 sis of the multiple origin of the Fungi from the 

 Algae has gained correspondingly in strength. 

 * * * 



' ' We can say, however, as noted above, that 

 the unlikeness in the method of spore-forma- 

 tion in the ascus and the sporangia which I have 

 studied, makes it impossible to assume any very 

 direct relationship between the Phycomj'cetes 

 and Ascomycetes. ' ' 



SHORT NOTES. 



Coulter and Rose contribute an important 

 paper to the Proceedings of the Washington 

 Academy of Sciences, consisting of a synopsis 

 of Mexican and Central America Umbelliferae, 

 in which all the data with respect to the um- 

 belliferous flora of the region under considera- 

 tion are brought together. Thirty-nine genera 

 and one hundred and eighty-two species are 

 enumerated. 



An interesting paper by O. Borge of Stock- 

 holm, on the fresh-water algae of Franz- Josefs- 

 Land (Siisswasseralgen von Franz-Josefs-Land, 

 Kongl. Vetens. Akad. Forhandl, 1899) enumer- 

 ates the plants collected by the Jackson-Harms- 

 worth Expedition. No less than forty-three 

 species, representing twenty-two genera, are 

 enumerated. These genera range from Oscilla- 

 toria, Nostoc, etc., to Cosmarium, Spirogyra, 

 Vmicheria and Oedogonium. One new species 

 is described, namely, Monostroma fisheri, of 

 which, oddly enough, a variety, also (var. 

 minor) was found. 



C. G. Lloyd continues his ' Mycological 

 Notes ' (No. 4, November, 1899) and takes up 

 the genus Psalliota, describing six species and 

 varieties, and enumerating eighteen or twenty 



