322 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of two adjacent carpel-like members of the outer series. There was 

 never any trace of a central placenta, and the author regards the 

 appearance of the ovules in the unique case as a proof of the origin of 

 the central placenta in normal flowers from the united edges of the 

 carpels. 



Monstrosities in Foliage Leaves.* — L. Geisenheyner describes and 

 figures some abnormal leaf-forms. On shoots of Deutzia crenata bearing 

 leaves of normal form, other leaves were found showing various stages 

 of union ; the author figures a shoot showing a terminal " compound " 

 leaf derived from the union of four displaced simple leaves. He also 

 describes pitcher-formations, involving the whole or part of the leaf 

 in Magnolia Yulan, and cases of forking of the mid-rib in leaves of 

 the common Ivy, accompanied with a greater or less indentation or 

 lobing of the central leaf -segment. 



Mobius, M. — History and description of the Botanic Garden at Frankfort-on-the 

 Main. Ber. Senckenb. Naturf. Ges. in Frankf.-a.-M., 1903, 



pp. 117-51 (2 pis. and 2 figs, in text). 



CRYPTOGAMS. 



Pteridophyta. 



Development of Vascular Cryptogams.! — G. Chauveaud, as a result 

 of his researches into their embryology, states that the stem of vascular 

 cryptogams is a complex structure. The first divisions in the quadrants 

 of the egg of a fern form a primary meristem, which by differentiation 

 yields a foot, a primary root, a primary leaf, and an undifferentiated 

 portion. The primary root and the primary leaf constitute a primary 

 plantlet, connected with the prothallus by the foot. Between the foot 

 and the primary leaf is the undifferentiated portion, forming a tiny 

 growing point which, when the first leaf has almost reached its complete 

 development, divides actively and forms a second meristem which, on 

 differentiation, gives a continuation of the foot, a second root, a second 

 leaf, and an undifferentiated portion. The second root and leaf form a 

 second plantlet similar to the first, and also connected with the preceding 

 structures by the continuation of the foot. When the second plantlet 

 has reached a certain development, the undifferentiated growing point 

 between the leaf and the foot again divides, and a third plantlet is pro- 

 duced — in short, the fern is built up by a succession of elementary 

 plantlets, consisting of root and leaf, connected by the foot. This 

 mode of formation becomes gradually less evident, owing to rapidity 

 of development resulting in the greater or less fusion of the successive 

 plantlets. The number of cells is also increased in each new generation, 

 and hence these generations, arising at levels less and less distinct, 

 cause a very rapid transverse growth of the structure formed by the 

 fusion of their parts. This body is what we know as the stem, the 

 structure of which becomes increasingly complex with the increasing 

 age of the plant. Thus the stem of ferns represents a fusion of dif- 

 ferent parts, the number varying according to the level of the section. 



* Ber. Daufscb. Bot. Gesell., xxi. (1903) pp. 440-51 (1 pi.). 

 f Comptes Itendus, cxxxviii. (1904) pp. 511-13. 



