ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 599 



in the young cone where the two alternating - sporangia of the whorl 

 below are appressed against it. It is suggested that it may be homolo- 

 gized with the free dorsal flap in S. pumila, here fused with the stem. 



4. The species of this type form a series, in which the dorsal outgrowth, 

 which originally served to protect the sporangia below, is gradually re- 

 duced and lost, while at the same time each sporophyll more and more 

 completely enfolds and protects its own subtending sporangium. In 



5. flabellata there is a transversely elongated dorsal projection, the 

 median portion of which extends freely downwards ; in S. caulescens 

 the free median portion is lost, and only a small curved ridge is left ; in 

 S. Vogelii and S. apus all signs of a dorsal projection at the base of the 

 sporophyll are lost. Finally, there appear to be in Selaginella a series of 

 forms of sporophyll, the most complex being found in one of the more 

 primitive species. This complex form presents a remarkable resemblance 

 to the form of the sporophyll in Lycopodium alpinum and L. cemmim, and 

 in Spencer ties — a significant resemblance, though not meaning close re- 

 lationship. The development of a complex sporophyll differentiated 

 into dorsal and ventral portions, in genera separated in time and in 

 general features so widely as are these three, seems to indicate that it 

 is a very ancient character. Otherwise it is an instance of parallel 

 development. 



Rhizophore of Selaginella.*— W. C. Worsdell writes on the mor- 

 phology of the rhizophore of Selaginella, discusses the views that have 

 been put forward about its morphological value, and describes his own 

 observations and experiments. He became convinced that the rhizophore 

 is of a shoot-nature, and that the very definite place of origin of the 

 rhizophores is a strong indication of their shoot-nature. 



Periderm-formation in Filicinean Petioles.| — H. S. Holden an- 

 nounces in a note that, having discovered a typical wound-periderm 

 in a Medullosean petiole, an account of which is about to be published, 

 he has been led to investigate a number of Filicinean petioles, mostly 

 of the Polypodiacese, with a view to determining whether a similar 

 response is exhibited by them. As a result, he finds that quite a 

 number of them show a well-marked wound-cambium, often several 

 cells in depth. 



Note on a Wounded Myeloxylon.J — H. 8. Holden gives an account 

 of the wound-tissue visible in a thin section of a fossil plant, a Myeloxylon 

 slide in Manchester Museum. Two to seven rows of periderm-cells, that 

 have arisen from a group of cambium-cells, are shown in some photo- 

 micrographs. 



Peculiar Fern ProthalliaJ — L. Pace describes some peculiar fern 

 prothallia, which, obtained on rotten wood from a swamp in Indiana, 

 have been in cultivation ever since. The summary of her observations 

 is that prothallia kept for three years in the laboratory in as nearly 

 normal conditions as possible, except for the absence of liquid water, 



* New Phytologist, ix. (1910) pp. 242-53 (figs.), 

 f Ann. Bot., xxiv. (1910) p. 611. 

 % New Phytologist, ix. (1910) pp. 253-57 (figs.). 

 § Bot. Gaz., 1. (1910) pp. 49-58 (figs.). 



