1893.] .MICROSCOJMCAL JOURNAL. 245 



stem (Fif^. 7). In still other instances the tip of the hyphu is 

 the seat of <;erniinative activity and, as in ligure 3, several bran- 

 ches can he seen arisinjj;. The liypha- are in some cases seen to 

 be divided by cross walls into separate cells ( Fij:. 7), this is not 

 the case in all the hypha-, and the younger parts are not divided. 



The aerial liypii;r are those that bear the conidia. They are 

 best studied on the edges of the growing mass. They are bran- 

 ched sparingly below but at the summit they branch abundant- 

 ly and so compactly as to form a broom-shaped mass (Fig. 9), 

 in which at first it is hard to recognize thebasidia and the rows 

 of conidia which they bear. A little separation of the mass with 

 needles, and gentle tapping on the cover glass, will helj) to dis- 

 engage the hyplue and render their terminations visible. It is 

 easy to realize after seeing the tips of these hyplue what count- 

 less myriads of conidia can be produced from a comjdete myce- 

 lium. There is no other mode of reproduction, commonly, if 

 ever, taking place in Penicillium. In this respect, it is worthy 

 of note, as in most fungi, there are provisions for the occurrence 

 of conjugation, a process in which the growth, at least part of 

 the time, arises from buds formed by the junction of two ele- 

 ments, or cells, jirior to active development. The process of 

 conjugation will be more fully described under the account of 

 Mucor. 



In the young submerged hypha^ it is very easy to make some 

 studies on the application of staining and other reagents to bio- 

 logical specimens. First, place a drop of stain, for instance 

 iodina, on one side of the cover glass. Then draw this under 

 the cover by means of a blotting paper placed on the other side. 

 This is called "irrigation" of the specimen. If you watch the 

 tips of the hypha' you will see them take up the color of the 

 stain. The same can be seen with any other stain for proto- 

 plasm. The protoplasm is thus demonstrated and vacuoles are 

 seen to be empty i daces surrounded with protoplasm. Any of 

 the aniline stains can be used in the same way. After the tips 

 of the hypha? are deeply stained, they can be decolorized and 

 the protoplasm dissolved while you watch the process at every 

 step, if you irrigate the same slide with a 2 per cent solution 

 of caustic potash in water. 



2. — Mucor. 

 This is anotiier of the commonest of the ''Moulds." It grows 



