100 SUMMARY OF CURRENT RESEARCHES RELATING TO 



octants form with one another an angle of 45°. When the octants, 

 unequal in size, separate from one another, the formation of tetraheclra 

 commences, but not simultaneously in all the octants. The macro- 

 spore proceeds from a tetrahedron, which is always surrounded by a 

 clear border, like that which distinguishes the tetrahedra, and which 

 may be attributed to the conversion into mucilage of the wall of the 

 special mother-cells. As the sporangial capsule grows, the proto- 

 plasmic ball, with the macrospore, becomes more and more closely 

 applied to one of the walls of the sporangium. The macrospore now 

 grows more rapidly, and its membrane begins to thicken, forming the 

 exospore. The tapetal cells still always retain their nuclei. In the 

 hardened epispore there appear more strongly refringent particles 

 between the vacuoles, which must be regarded as the remains of the 

 nuclei of the tapetal cells. The microsporangia form sixteen spore- 

 mother-cells. Each of the microspores is surrounded by a clear 

 border ; and here also the tapetal cells still retain their nuclei. 



Two teratological examples at this point were observed. One con- 

 sisted of a double sporangium, which was divided in a direction at 

 right angles to its longer diameter, each half forming its separate 

 archespore. The other was a hermaphrodite sporocarp, containing a 

 number of microsporangia and five macrosporangia. 



The author considers that the facts here recorded still further 

 accentuate the separation of the Rhizocarpefe into the two groups of 

 MarsileacesB and Salviniaceae. The sexual ditferentiation of the sori 

 in Salvinia must be regarded, from a phylogenetic point of view, as an 

 advance in structure in comparison with Marsilea ; the occasional 

 hermaphrodite sporocarps of Salvinia being referable to atavism. A 

 further evidence of advance is the formation of only eight spore- 

 mother-cells in the macrosporangium of Salvinia, in contrast to the 

 sixteen in Marsilea. Another indication of advance is that from this 

 point only one spore is required in order to produce a macrospore, 

 while in Marsilea one spore from each tetrahedron grows more rapidly, 

 one of these then developing into the macrospore. Whether the 

 Marsileacefe or the Salviniaceae is considered as the more advanced 

 group depends on the relative importance attached to the asexual or 

 to the sexual generation. Possibly the two are derivations from 

 a common ancestral form. 



Muscineae. 



Structure and Classification of Muscinese.* — S. 0. Lindberg 

 publishes a succinct account of the morphology of the entire group of 

 Muscineae, including both exotic and European forms. After con- 

 trasting the earliest stages of development with those of vascular 

 cryptogams, he describes the germination and the protonema-stage, 

 the root, the stem, the leaves, the " inflorescence," the sexual organs, 

 the sporogonium, and finally the spore-plant, composed of calceolus, 

 seta, theca, and spores. Under each heading, the Hepaticae, Sphag- 



* Lindberg, S. O., * Europas och Nord Amerikas hvitmossor (Sphagna) 

 jamte en inledning om utvecklingen och organbildningen inom luossornas alia 

 tre gnipper.' (Swedish with Latin diagnoses.) 116 pp. Helsingfors, 1882. See 

 Bot. Centralbl., xi. (1882) p. 373. 



