Febeuary 23, 1900.] 



SCIENCE. 



303 



from those previously recorded were re- 

 ferred to. It was shown that the habit of 

 the plant is not that of a universal endo- 

 phytebut is quite as often merely epiphytic. 

 The character of the chromatophore was 

 found to vary from the ' one-sided ' ar- 

 rangement, considered by Reinhard as typ- 

 ical, to a condition where the cell wall was 

 completely lined by the color body. Two 

 sizes of zoospores, formed by successive di- 

 visions, were described, but no suggestion 

 of conjugation could be observed and it 

 seems probable that nothing of the kind 

 occars. In the material examined the dis- 

 charge of zoospores was found to take place 

 through a circular opening of considerable 

 size instead of through a tubular neck as re- 

 corded by European writers on this subject. 

 The paper will be published in full later. 



The roots and myeorhizal adaptations of the Mon- 

 otropacece: Professor]D. T. MacDougal, 

 New York Botanical Garden, and Pro- 

 fessor F. E. Lloyd, Teachers College. 

 (By invitation.) 



The MonotropacesB have been under in- 

 vestigation with respect to their mycorhizse 

 since 1840. Of the genus Monotropa, M. 

 Sypopitys only has received consideration, 

 and all references made in text-books hith- 

 erto have referred to this plant. Monotropa 

 uniflora has now been added to the list. In 

 this plant the roots are found to be entirely 

 invested by the mycelium of the fungal 

 symbiont, even over the cap. The latter 

 is 2-4 cells in thickness but arises from a 

 calyptro-dermatogenic layer. The plerome 

 and periblem arise from a common initial 

 tissue and may not be distinguished for 

 some distance back from the apex. The 

 stele and cortex arising therefrom are not 

 distinctly delimited, there being no well 

 marked endodermis. The stele is very ir- 

 regular in structure. The hyphse of the 

 fungus gain access to the epidermal cells at 

 about the backward limit of the root-cap, 



but never enter these. The short hausto- 

 rial branches which gain entrance enlarge 

 into more or less irregular vesicles, and 

 these come partly to surround more or less 

 the nucleus which, however, does not become 

 hyperchromatic, but maintains its normal 

 condition for a long time. The epidermal 

 cells ultimately become separated from 

 each other by the hyphse which penetrate 

 between them, but not between the cells of 

 the cortex, or only very rarely. The vesi- 

 cles sometimes produce spore-like bodies 

 and are believed to be reproductive. A 

 most interesting gradation from the arrange- 

 ment of the mycorhizas in the nearly re- 

 lated Pyrolas is shown. The branching of 

 the root in ML uniflora is exogenous, this 

 result not according with that of Kamien- 

 sky on Hypoitys. 



The general statements which may be 

 made concerning all the Montotropacese 

 now studied with reference to their mycor- 

 hizas are as follows : 



1. The shoots are free from chlorophyll, 

 and have no stomata except in the case of 

 Pterospora. 



2. The customary relations in size of the 

 root and shoot are lost. 



3. The stele is much reduced in both the 

 shoot and root, and shows perforated ves- 

 sels and companion cells only. 



4. The fungus sheathing the root encloses 

 the tip completely, at least at certain sea- 

 sons, and penetrates the epidermal cells in 

 all of the genera examined. Vesicles, spor- 

 rangioids or organs of interchange are 

 formed in the epidermal cells. The relation 

 between the fungus and the seed plant is 

 a pure sj^mbiosis and the latter does not 

 act as a fungus trap in accordance with 

 Frank's theory. 



5. The root cap is one to many layered, 

 and with the epidermis is derived from a 

 dermato-calyptrogenic layer. The periblem 

 and plerome are not distinguishable in 

 form or content. 



