1 14 Morphology BOOK i 



In the fourth edition of the Lehrbuch important changes 

 were introduced, in the light of the knowledge of the 

 reproductive processes which had been obtained. Sachs 

 proposed four classes of Thallophytes, and included in each 

 forms with and without chlorophyll, thus abandoning the 

 idea that a fundamental division exists between Algae and 

 Fungi. In this he followed Cohn, who had made a similar 

 proposal in 1872. His classes were based upon the manner 

 of the reproduction prevalent in each. The first was 

 Protophyta, in which he included the blue-green Algae 

 and the two groups of the Bacteria and the Yeasts, in which 

 no sexual fusions had been observed. The second class 

 included all the forms in which sexual reproduction was 

 found to take the form of the fusion of similar gametes 

 or sexual cells, no difference of sex being noticeable. He 

 called it Zygosporeae from the zygospore, the product 

 of such fusion. His third class, Oosporeae, included the 

 forms which showed the fertilization of a female cell, or 

 oosphere by a motile antherozoid; and the fourth, Carpo- 

 sporeae, those in which the product of fertilization is 

 a complex fruit-like body. Among these he recognized an 

 alternation of generations comparable to that which is 

 presented by the higher plants. 



This separation of the Algae and Fungi into two parallel 

 series, though indicating the affinities existing between 

 the two groups, did not obtain permanent acceptance by 

 botanists. The classification of the Fungi which we owe 

 to the writings and work of De Bary was more satisfactory, 

 and has remained, with some inevitable modifications, 

 practically unchallenged, though a certain re-arrangement 

 of his main groups was suggested by Brefeld many years 

 later. 



The recognition of Bacteria as vegetable organisms was 

 due to Cohn, in 1853. At first they were held to belong 

 to the fungi, and were long known as Schizomycetes. The 



