HALF-AX-TIOT'I! AT TTTK :\ITrR()SC()PE. 323 



Incoagulable Albumen (a new culture medium).^— M. E. 



Marchal has devised an albuminous solution, with which he has 

 successfully cultivated a large number of bacteria, both patho- 

 genic and saprophytic. The solution is prepared as follows : — The 

 white of fresh eggs is diluted in distilled water and filtered. A 

 solution of 1/ looo of iron sulphate is then added to the albumin- 

 ous liquid in the following quantities : — 



Albuminous solution, i — 5 per cent., i — 5 centim. cubes per litre. 



55 V 5 10 5' 5 10 M » 5» 



„ „ 10 — 15 „ 10 — 15 „ ,, ,, 



The iron sulphate has the curious property of preventing the 

 coagulation of the albumen by heat. The liquids can be sterilised 

 at once in an oven at iis'^. The medium thus prepared is per- 

 fectly limpid, its reaction being slightly alkaline M. Marchal finds 

 that this solution is very easily and rapidly prepared, and it advan- 

 tageously replaces the ordinary bouillons in use. 



Ibalf-an^lbour at tbc fIDicroecope, 



Mitb (tbe late) mv. TLnttcn Mest, jf.XS., jf.lR./ID.S., 



etc. 



Callithamnion roseum (PI. X., Figs, i — 8).^The origin of 

 fruits by metamorphosis of branches into specialised structures of 

 a higher type is beautifully shown. Two forms of fruit are seen. 

 Special care must be taken to distinguish from fruits certain para- 

 sites, which are growths from spores of other attached algae. 

 Decurrent branches, adherent to the main stem, may also be seen 

 with care. These have a peculiar interest, as shadowing out 

 remarkable developments, in some other algae, as Batrachospermum ^ 

 and notably in species of a foreign genus, Balliu, in which they 

 are developed to a remarkable extent. The medium employed in 

 mounting (Ayl ward's fluid) appears to be a valuable addition to 

 our materials for this purpose. I have seen Acari beautifully 

 [)reserved in it, and should much like to know the formula for its 

 preparation. 



* Bull. So(\ Beige Micr., xix. (1893), PP- ^4' ^S- 



