SODA. 



[ 582 ] 



SPERMATOZOA. 



SODA. Kolliker recommends a solution 

 of caustic soda, in preference to potash, for 

 the resolution of some of the tissues into 

 their component elements. We have been 

 unable to detect any marked difference be- 

 tween the action of these two solutions; 

 and the former has the disadvantage of lift- 

 ing the stopper from the bottle by the cry- 

 stallization of the carbonate formed, so that 

 it is with difficulty preserved. 



SODIUM, CHLORIDE OF, or common 

 salt. The crystals of this salt belong to the 

 regular. system. The most common form is 

 the cube terminated by quadrangular pyra- 

 mids or quadrangular pyramidal depressions, 

 rectangular tables, &c. Schmidt endeavours 

 to show that the primary form of the cry- 

 stals is the octohedron, and that the cubes 

 are twin octohedra. The crystals do not 

 polarize light. 



BIBL. Schmidt, Entwurf. e. dllg. Unter- 

 such. fyc. 90, and the Bibl. of CHEMISTRY. 



SCEMMERING, MIRROR OF. INTRO- 

 DUCTION, p. xix. 



SORUS. The name applied to the ag- 

 gregation of sporanges of the FERNS ; some- 

 times applied also to the groups of spores 

 in the Florideous Algae. 



SPATHIDIUM, Duj. A genus of Infu- 

 soria, of the family Leucophryina. 



Char. Body oblong, thicker and rounded 

 behind; thinner, broader, and obliquely 

 truncate in front. 



S. Tiyalinum (Leucophrys spathula, E.) 

 (PL 24. figs. 75 & 76). Hyaline; anterior 

 margin with irregularly arranged minute 

 black points. 



Ehrenberg figures a row of cilia at the 

 anterior end of the body. 



BIBL. Dujardin, Infus. p. 458. 



SPERMATIA. The minute corpuscles 

 supposed to represent spermatozoids in the 

 LICHENS (PI. 29. figs. 3, 15, 16) and FUNGI 

 (PI. 20. figs. 2, 3, 4). 



SPERMATOZOAorSPERMATOZOIDS, 

 OF ANIMALS. The form of the spermatozoa 

 varies in different animals (PI. 41), but they 

 usually consist of a rounded or oval body or 

 head, to one end of which is appended a 

 moveable filament. This is their form in 

 man and in the Mammalia generally. 



In Birds, the body is sometimes cylindri- 

 cal, sometimes spiral, or presenting a zigzag 

 outline. 



In Reptiles the body is usually cylindrical 

 and straight, sometimes spiral. But in some 

 of them the straight or slightly undulating 

 terminal filament is surrounded by a spiral 



filament, which some observers have regarded 

 as an undulating membrane (UNDULATING 

 MEMBRANES). 



In Fishes, the spermatozoa are usually 

 very small, and the body round, although in 

 others the body is spiral. 



In the Invertebrata, a distinct body and 

 terminal filament are present in some, whilst 

 in others each spermatozoon represents a 

 simple filament tapering at the ends. In 

 some of these the body seems alone to exist 

 in the form of a short cylinder or rod. In 

 others the spermatozoa are represented by 

 simple cells, or cells with radiating pro- 

 cesses. 



The curious filaments, one of which is re- 

 presented in PI. 14. fig. 20, we found within 

 the body of a Cypris. There were several 

 together, in those containing as well as in 

 those not containing ova, and they consisted 

 of two spiral fibres. We at first considered 

 them as spermatozoa ; but finding that they 

 resisted the action of a boiling solution of 

 potash, which renders all other spermatozoa 

 invisible or dissolves them, we hesitate as to 

 their nature. They bear some resemblance 

 to the elaters of Trichia. 



The exact manner in which the sperma- 

 tozoa are developed is not decided. 



According to Kolliker's observations, they 

 are developed within cysts or (epithelial?) 

 cells contained in the tubuli testis, or other 

 form of seminal organs. A number of nu- 

 clei or globules arise within these, in each of 

 which a spermatozoon is afterwards found 

 lying coiled up. On the solution or rupture 

 of the globules, the spermatozoa become 

 free within the cysts. In some animals the 

 spermatozoa are formed in bundles, the bo- 

 dies and filaments lying parallel with and 

 opposite each other. 



According to Reichert and Quatrefages, 

 the transparent and homogeneous sperma- 

 togenous masses undergo a process of seg- 

 mentation analogous to that occurring in the 

 ovum, reducing them to a granular state, 

 the filaments being subsequently formed. 



Most spermatozoa exhibit active move- 

 ments produced by the action of the fila- 

 ment, whence they were formerly considered 

 as independent living animals. This notion 

 is now abandoned, the movements being 

 undoubtedly comparable to those of the 

 ciliated zoospores of the Algae, or the ciliated 

 epithelial cells of animals. 



In some animals tubular sheaths are se- 

 creted around the masses of spermatozoa 

 whilst contained in the seminal apparatus, 



