Febeuaey 26, 1897.] 



SCIENCE. 



355 



able to observe certaiu of the resting cells 

 formed by the conjugation of two microzoo- 

 spores. 



In his studies upon Botrydium granulatum he 

 determined by pure cultures that what has been 

 regarded as a remarkable pleomorphic species 

 really represents two distinct species. His at- 

 tention was first called to this confusion by the 

 difference in the cell structure of the various 

 forms. lu one the chlorophyll bodies are in the 

 form of distinct discs, while in the other the 

 chlorophyll is a single connected plate. In one 

 the cells form a fatty oil but no starch, while 

 the other possesses amylon grains and starch 

 bodies, their structure being like that of the cell 

 of Hydrodictyon. One of these plants is a true 

 Boirydium, while the other is the Protococcus 

 botryoides, described by Kuetzing in 1845, and 

 in 1855 Cienkowski correctly described its de- 

 velopment. Since the genus Protococcus is un- 

 tenable, Klebs proposes the name of Protosiphon 

 botryoides for this plant. 



He takes occasion to deplore the tendency of 

 some algologists to repeat in the case of the al- 

 gBB the pleomorphic craze which once brought 

 such confusion to bacteriology and mycology, 

 citing especially Hansgirg, in 1855, and the 

 more recent work of Borzi and Chodat, who 

 claim to have connected a large number of gen- 

 era in the form cycle of one species. He 

 points out that these investigators did not use 

 pure cultures and were thus led to include in 

 the form cycle different genera appearing in 

 the culture. It has been held by some that if 

 filamentous algse possess protococcoid forms in 

 one stage of development, then all protococ- 

 coid forms are states of filamentous algse. It 

 is impossible to distinguish the swarming ga- 

 metes of Chlamydomonas and Ulothrix, still it 

 does not follow that Chlamydomonas belongs to 

 Ulothrix. He insists that in studies of devel- 

 opment pure cultures should be used, though 

 pure cultures in the sense in which they are 

 made in bacteria and the fungi cannot be made. 

 Pure cultures and continuity of observation, es- 

 pecially in connecting different stages, should 

 be substituted for mixed cultures and discontin- 

 uous observations. 



Space will not permit a discussion of his ex- 

 periments upon other genera of algse and the 



fungi, but the following outline of his experi- 

 ments upon Vaucheria will give an idea of the 

 thorough and comprehensive manner in which 

 his work was conducted. 



I. The asexual reproduction through zoospores of 



Vauvheria repois and clavaia. 



1. Influence of nourishment. 



2. Influence of dampness. 



3. Influence of light; of darkness; of weak light; 



of the rays of the spectrum; of light intensity; 

 of carbon assimilation. 



4. Influence of temperature; low temperature; high 



temperature; mean temperature and. variations 

 of temperature. 



5. Influence of the chemical peculiarities of the 



medium. 



A. Inorganic compounds; effect of nutrient salts; 

 change from nutrient salts to water. 



B. Organic compounds ; cane gugar ; camphor. 



C. Osmotic value of the compounds. 



D. Influence of acid or alkaline reaction. 



E. Influence of oxygen ; influence of air pressure; 

 of rarified air. 



F. Influence of flowing water; of friction; of 

 temperature ; of oxygen and nutrient salts. 



II. The asexual increase in the case of other species 



of Vaucheria: Vaucheria ornithocephala; ap- 

 lanospores of V. geminala; conditions of their 

 formation; aplanospores of V. racemosa, unci- 

 naia. 



III. The sexual reproduction of Vaucheria. 



1. Influence of light. 



A. Effect of light as a means of nourishment. 



B. Influence of light intensity. 



C. Significance of colored light. 



2. Influence of dampness. 



3. Influence of temperature. 



4. Influence of chemical peculiarities of themedium. 



5. Influence of oxygen. 



6. Influence of flowing water. 



7. Upon the relation of the male and female sex. 



Geo. F. Atkinson. 



COENELL UNIVEESITY. 



Codice Messicano Vaticano, No. 3773. Edizione 

 DEL DucA DE LouBAT. Roma. 1896. 

 In the native literature of America that 

 which was the product of aboriginal authors, 

 the pictographic manuscripts, or 'codices,' as 

 they are called, of Mexico and Central America, 

 hold the first rank. Quite a number of them, 

 though generally in an imperfect condition, have 

 been preserved which date from before the 



