278 BIOLOGICAL LABORATORY OF SYDNEY UNIVERSITY, 



equilibrium of the alcohol and chlovoforin Ordinary objects may 

 simply be transferred from absolute alcohol to chloroform and kept 

 in the latter for twenty-four hours, or until saturated. Saturation 

 with paraffin is then eflfected by the well-known method of Gies- 

 brecht. I use a special water-bath with troughs divided into a 

 number of compartments. To ensure a good result equal parts by 

 volume of chloroform and paraffin (of low melting point) should 

 be used, and the objects should be left in the bath at the temper- 

 ature of the melting-point of the soft paraffin for about twenty-four 

 hours. 



To ensui-e sufficiently fine and delicate sections to obtain the 

 full advantage of the process of staining described above, Caldwell's 

 or some other good form of automatic microtome must be 

 employed, a coating of soft paraffin round the hard in which the 

 object is embedded being added, according to Caldwell's invaluable 

 process, to prevent curling and secure series if required. Sections 

 so prepared and cut can be kept unaltered for an indefinite length 

 of time. 



To prevent the sections breaking up or becoming disarranged 

 during che process of mounting in balsam^ it will be found desirable 

 in most cases to fix them down to the slide. For this purpose the 

 best agent is Caldwell's shellac dissolved in creosote, which gives 

 much better results than the gum arable which I previously used 

 and recommended. 



3. Minute Structure of Polyno'e. 



In a short paper in the Zoologischer Anzeiger, Jordan has recently 

 described the histological structure of the scales of Polyno'e as 

 revealed by making series of sections. His figures and description 

 agree exactly with what I find to exist in species which I have 

 examined, except that he omits to notice certain cells which I find 

 in the tissue of the scale. The nerve which enters the elytron 

 ramifies through the scale and the ultimate twigs mostly end 

 in minute processes on the surface. Just before the nerve 

 twig enters this end-organ it passes through a little ganglion. 

 These ganglia are mostly composed (and Jordan represents them 



