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Sphaeraphides were more or less rounded, often spherical bodies, 
made up of white or opaque crystals or crystalline matter. In some 
the ends of the component crystals projected, and gave them a star- 
shaped appearance. They were much smaller than their cells, and, 
in somé cases, were thickly studded throughout the cellular tissue. 
This was the case with many ‘of the cactus family, some of which, 
when aged, had their tissues so filled with them as to render the plants 
very brittle. It was mentioned that plants of C. Send/is, reported 
- over a thousand years old, when sent to Kew Gardens, had to be 
packed in cotton as carefully as if they were delicate glass or jewellery. 
The fruit of the prickly pear was full of Sphaeraphides, examples of 
which were easily seen in the crane’s-bills, elm, beet, spinach, or 
- violets. 
Crystal prisms were found either singly or two, three, or at most 
four, together in combination within the same cell. While under a low 
power raphides did not present angles or faces, crystal prisms pre- 
sented both ; instead, too, of tapering to a point at both ends, they 
were wedge-shaped or angular. Some were three or four-sided, while 
others were octohedrons. They were larger than raphides, and were 
not, as a rule, easily separated from the tissues in which they were 
seated. Examples might be found in the green-pea shell, the garlic, 
green fig stem, gladiolus, &c., and very abundantly in the soap tree of 
South America, used in Peru as a substitute for soap in the cleansing 
wool or hair, or in washing. 
Chemically, plant crystais were chiefly composed of oxalates of 
lime and magnesia, or phosphate of lime. 
Professor Gulliver’s researches showed that so persistent were 
raphides in certain families of plants and so absent in others, that it 
was possible to differentiate, at all stages of their growth, between 
plants otherwise apparently allied. Thus Onagraceae and Galliaceae 
abounded in raphides, while none of their near neighbours contained 
them. So likewise the red berries of black-bryony and cuckoo-pint 
could be distinguished from those of red-bryony and guelder-rose, by 
_ the presence in the first two and the absence in the last two of 
 —raphides. 
To the botanical student, characters such as those indicated were 
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_ of very great value, and to the microscopist a wide field of research 
was opened, for not only would he find plants containing one or other 
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