JOURNAL OF MICROSCOPICAL SCIENCE. 



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EXPLANATION OF PLATES I, II, & III, 



Illustrating Mr. Marshall Ward^s Paper on Hemileia 



vastatrix. 



Figs. 1 — 3. — A uredospore detached in water, and viewed in various 

 positions by rolling : the contents are omitted for simplicity. Zeiss J., 

 CO. 4. Fig. 1, a, c, and Fig. 2 a, are seen from the side ; Fig. 1 b, from 

 above ; Fig. 2 b, from below ; Fig. 3, from the end by which spore would 

 be attached. 



Fig. 4-. — Similar spore seen in (oblique) transverse optical section, 

 Zeiss J., oc. 4. 



Fig. 5. — A similar spore, with oily drops among the orange-coloured 

 contents (a) ; after pressure these are driven out (b) aud float free. 

 Zeiss J., cc. 4. 



Fig. 6. — A spore to which dilute glycerine was added : the withdrawal 

 of water demonstrates the presence of the endospore (o). Careful wash- 

 ing causes the gradual resumption of original state {b and c). The spore 

 is viewed obliquely from one end. Zeiss E., oc. 4. 



d, piece of exospore in section. Zeiss J., oc. 5. 



Fig. 7. — Uredospores which have become filled with vacuoles after lying 

 in water for several hours. In series a the vacuoles (i) disappeared on 

 addiug (ii) weak iodine solution ; no reappearance (iii) after washing. On 

 addition (iv) of potash the contents become clearer, and the exospore 

 swells. Series b, a similar spore before and after treatment with weak 

 sugar solution : the vacuoles go, and the endospore contracts away from 

 exospore. In c, are similar results obtained by adding sodium chloride 

 solution, the endospore becomes wrinkled and contracted, d, vacuolated 

 spore before and after treatment with weak potash. All Zeiss E., oc. 4. 



e, similar fresh spores more magnified. All optical sections. Zeiss 

 J., oc. 5. 



Fig. 8. — Uredospores at the commencement of germination (in water) : 

 the endospore protrudes at three or four points, forming delicate tubes 

 into which the coloured granular contents slowly pass. The clearer spaces 

 are vacuoles (sap cavities) ; a beautiful streaming motion is often seen in 

 the germinal tubes, a had been sown twelve hours ; b, the same 

 spore, five hours later. Zeiss J., oc. 4. 



Fig. 9. — Similar preparations : a, after eighteen hours in water; b, same 

 after twenty-two hours ; c, same after thirty hours. All Zeiss J., oc. 4. 



Fig, 10. — A uredospore after twenty-four hours' germination in water. 

 Zeiss J., oc. 4. 



Fig. 11. — Two similar objects after thirty hours' germination in water. 

 Zeiss E., oc. 4. 



Fig. 12. — Uredospore after about forty hours' germination in water : 

 be curved, branched, and even-coiled germinal tube forms a pyriform 

 welling at apex, into which the contents pass. Zeiss D., oc. 4. 



