27S SUMMARY OF CURRENT RESEARCHES RELATING TO 



natural cultures. In the former case ho did not succeed in carrying 

 tho development further than De Bary had done some time ago with 

 L. inundatum, but the prothallia which he discovered at Buitenzorg 

 in Java, under spontaneous conditions of development, fitted in exactly 

 where the others stopped. 



The adult protliallium is a very singular structure, consisting of a 

 short cylindrical axis, half immersed in the soil at one end, where it 

 is furnished with root-hairs. The upper extremity bears a tuft of 

 small leaf-like lobes. Tlio archcgonia and antheridia arc found on 

 the upper part of the cylindrical axis, forming a kind of ring or crown 

 near the tuft of lobes. The prothallium therefore presents a type 

 moridiologically more differentiated than is met with elsewhere 

 amongst the vascular cryptogams. While this is the case with the 

 sexual generation (oophore), the spore-bearing generation (sporo- 

 phore) in its embryonic stage is less differentiated than is the case, 

 for example, in the fern. The embryonic root is supi^rcssed, and tho 

 whole embryo, which is wholly parenchymatous, approximates in its 

 morphological characters to those of the prothallium. 



The prothallium of Lycopodtum * has also been met with again 

 by H. Bruchmann in the case of L. annotinum. He describes it as a 

 minute tuber, of a dirty white and felted appearance, and entirely 

 destitute of chlorophyll. The young plants were already from 12 

 to 20 cm. in length, considerably branched, and probably two years 

 old. The description of the prothallium agrees in the main with 

 that of Fankhauser. The tissue of the vegetative portion may be 

 distinguished into four layers. The layer next to the upper side of 

 the prothallium is completely filled with nutrient substances, proto- 

 plasm, oil, and starch. Below this is a row of palisade-like cells, 

 with their longer axis at right angles to the surface ; and next to this 

 again a layer of cells of more tabular form. The cells of all three 

 layers contain nuclei and nucleoli. The fourth layer or epidermis is 

 sharply differentiated at the basal part of the prothallium. It is 

 cuticularized on its outer surface, and from it proceed the rhizoids, 

 which are often as long as the prothallium itself. The further 

 growth of the prothallium depends on cell-division at its margin. 



The antheridia vary greatly in size and form. The antheridial 

 sacs formed in the centre of the cushion of tissue are the largest ; 

 those at the margin are smaller, and apparently abortive. They are 

 oval in form, and lie in large numbers very close to one another. 

 Their walls differ in no respect from those of the other cells of the 

 prothallium, and they are covered outwardly by one or more layers 

 of cells, which become disintegrated when the antheridia discharge 

 their contents. The interior of the antheridium consists of a large 

 number of polyhedral cells, which should, by analogy, be the mother- 

 cells of the antherozoids. But, according to the author, their walls 

 become, when ripe, converted into mucilage, and discharge each, not 

 a single antherozoid, but ten or more small colourless cells, out of 

 which the same number of excessively minute motile bodies, appa- 



* Bot. Ceutralbl., xxi. (1885) pp. 23-8 (1 pi.). 



