36 PKOGRESS or MICROSCOPICAL SCIENCE. 



there is an entii-o series of steps frum tlie completely dioecious arrange- 

 meut to that in which self-fertilization is the rule even if it has 

 exceptions. There are, for instance, some examples of dioecious 

 grasses, then a number of moncecious, after which follow some with 

 both hermaphrodite and staminate flowers, where the latter only can 

 serve for crossing ; then, in greater number, gi'asses with purely 

 hermaphrodite flowers ; in some of which the pistil develops before 

 the anthers ; in others, where the pistil and anthers develop simul- 

 taneously, the discharge of pollen from the anthers lasts for an 

 apijreciably longer time ; but there are some cases where the pistil 

 and anthers ajipear to develop together and have the same duration, 

 but yet under such conditions that the pollen can reach the pistil only 

 with difficulty. And finally some grasses in which close fertilization 

 is not avoided, but actually occurs in a large proportion of cases, and 

 even prei)onderates ; yet even in these instances occasional cross- 

 fertilization does not appear to be excluded. So that fertilization in 

 grasses, as in other families of plants, must be studied, species by 

 species, and we cannot apjdy our observations of one species to another 

 species even of the same genus. Thus the genera Hordeum, Avena, 

 and Triticiiin exhibit great diversities in respect to fertilization in 

 their several species. 



Hie Structure of Striped Muscular Fibre. — Mr. E. A. Schafer has 

 communicated to the Eoyal Society at one of its recent sittings, a 

 paj^er on the above subject, which is of so much importance that it 

 almost promises to completely revolutionize histological science. The 

 author, after premising that, owing to the rapidity with which changes 

 set in after death, the subject in question can only properly be worked 

 out whilst the muscular fibres are still living, the author i^roceeds to 

 give the result of his investigations of the tissue in this condition. 

 The animal employed was the common large water-beetle, the muscles 

 of the legs being taken. These were examined entirely without addi- 

 tion, being either teazed out upon a glass slide in the ordinary way 

 and covered with thin glass, or else prepared upon the latter, which 

 was then inverted over a ring of putty after the method inti'oduced by 

 Strieker. The author describes a muscular fibre as consisting of a 

 ground-substance appearing at first sight to be formed of two distinct 

 substances (the one dim, the other bright in aspect, which are arranged 

 in alternating disks disposed in successive series, with their planes at 

 right angles to the axis of the fibre) and of a vast number of minute 

 rod-like jjarticles, to which he applies the term muscle-rods, which are 

 closely arranged side by side and parallel to the axis of the fibre, so 

 as to form by their juxtaposition as many series as there are disks of 

 dim substance in the fibre. The main part or shaft of each muscle- 

 rod is imbedded in and traverses a disk of dim substance, while the 

 ends, which are enlarged at the extremity into little knobs or heads, 

 extend into the bright disks. These little knobs it is which give the 

 appearance of the line of dots which has long been described as existing 

 in the middle of each bright stripe ; when the fibre is somewhat ex- 

 tended this line appears double, owing to the separation of the heads 

 of the two successive series of muscle-rods which meet in the middle 



