ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



511 



B. R 



:fl 



tine cambric, or bolting silk, fastened on with thread ; this cap must 

 come above the holes/; the inferior surface is then dipped into collodion, 

 in order to render the bottom of the tube impermeable to fluids, any inter- 

 change of menstrua taking place through the holes/. The Orthonectids, 

 or other small organisms, are placed in the 

 expanded portion of the tube by means 

 of a capillary pipette, and then the tube 

 inserted in the stopper of a small glass 

 cylinder (fig. 134 B), which is destined for 

 the various reagents. In this way the 

 animals are fixed, cleared up, and pa- 

 raffined, without loss or damage. When 

 impregnated with paraffin, the tube is 

 solidified with cold water, the cap is re- 

 moved, and slight heat allows the block to 

 be removed from the tube. The block is 

 then sectioned. The sections, about 10 /a 

 thick, were stained with iron-hasrnatoxylin. 



Collecting and Examining Larval } \\ f 



Nephridia of Polygordius.* — C. Shearer 

 obtained the material from the Naples 

 Zoological Station in 1002 ; the adult 



worms containing the sexual products being c--" *3}gs f' 



broken up in small jars of fresh sea-water, 

 when the ripe eggs and spermatozoa readily 

 separate out. The sexual products remain Fig. 134. 



suspended in the water while the broken 



fragments of worms and debris fall to the bottom of the jar, when they 

 can be readily drawn off. The jars are set aside until fertilisation 

 has taken place. The first signs of cleavage appear some three or 

 four hours later. The eggs are then stirred up and washed in several 

 changes of sea-water to remove unnecessary spermatozoa. Development 

 proceeds rapidly and steadily till the third day, when they must be fed, 

 otherwise they atrophy and eventually break up. 



For sectioning, the combined celloidin-paraffin method was adopted, 

 the material having been fixed in Flemming's strong solution or in 

 Hermann's. The sections were stained with hajmacalcium or some 

 hamiatoxylin solution ; while for larva? to be studied whole, dilute 

 picro-carmin, followed by slight acid-alcohol, gave satisfactory results. 



The larva of Polyyordias is found in the " tow " abundantly during 

 the months of February, March, and April ; it is possible also to rear the 

 larva from the egg throughout all the summer and winter months. 



Collecting and Examining Dolichoglossus pusillus.f — B. M. Davis 

 obtained the material from mud flats which at low tides are uncovered. 

 When a favourable site is located a spadeful of mud is dug up and the 

 burrow of each animal carefully examined for eggs. By breaking down 

 one side of the burrow and gently lifting the animal out, or pushing it 



* Phil. Trans., cxcix. (1908) pp. 199-230 (4 pis.). 



t Univ. California Publications (Zoology), iv. (1908) pp. 197-226 (5 pis.). 



