306 Transactions. — Zoology. 



five, two''' could not afterwards be obtained, despite my endea- 

 vour. These forms were killed by immersion in 60-per-cent. 

 spirit, and afterwards hardened in alcohol of various grades 

 up to 86 per cent. : a course of treatment which gave excellent 

 results despite its primitive character. A subsequent visit in 

 the month of September gave three new speciesf (and several 

 varieties which lack of time prevented me from fully examin- 

 ing), in addition to the duplicates of the earlier collection. 

 These were all removed to the laboratory in their native ele- 

 ment, and, after careful observation in the living condition, 

 were killed, some by osmic acid, others by the slow spirit 

 method (Elsig's), and others by picro-sulphuric acid. As far 

 as the materials would allow, each species was ti'eated in all 

 three ways : where the colony was too small to divide, the slow 

 spirit killing was followed, as its greater simplicity involved 

 less risk. Good results were, however, obtained in all cases. 



For staining pui'poses picro- and borax-carmine were 

 chiefly employed, both being used in every case except the 

 osmic-acid specimens, which were transferred directly to picro- 

 carminc. The picro-carmine was used for staining the 

 "conn" or " ascidiarium " in its entirety before imbedding 

 and sectioning. Other subjects, previously imbedded and 

 sectioned, were either mounted in the natural condition or 

 stained in borax-carmine or iodine. The picro-carmine stain- 

 ing proved much superior under the microscope, as it gives 

 greater diiferentiation in tint, and is more transparent. 



It was found necessary to decalcify the three species of 

 LciHoclinum — L. nivenm, L. densum, and L. tuberatum — before 

 any satisfactory examination could be made. This was accom- 

 plished by the use of a weak solution of hydrochloric acid in 

 86-per-cent. spirit, the acid being added drop by drop till small 

 bubbles of gas began to rise, fresh acid being added when the 

 effect of the first was neutralised. In this way decalcification 

 took place slowly and gently with the least possible injury to 

 the tissues. The results were, in each case, excellent. Speci- 

 mens so treated were, after the removal of all traces of acid, 

 stained and mounted in the usual way. 



Sections were made both longitudinally and transversely 

 to the axes of the zooids, or, more properly speaking, parallel 

 and at right-angles to the surface of the colony, since the 

 zojDids are seldom arranged quite perpendicularly to the ex- 

 terior boundary of the test. In all cases the sections were 

 taken by hand. Cystoclytes a^icklandicus, on account of its 

 larger size and the opacity of its mantle, was prepared by 

 saturation with parafiBn, &c., for sectioning in the rocking 



* C. perspicuus and P. paradaxum. 



I C. aiicklandicus, F, fuscum, and L. maculattwi. 



